Abstract: The rapid and accurate monitoring of the grain storage is an important problem to be solved by the national food regulatory authorities. This study developed an on-line monitoring system of grain storage based on the 3-D laser scanning technology to realize the on-line real-time monitoring of grain storage. The system consisted of a hardware system based on a 3-D laser scanner and a point cloud data processing software system. The hardware system mainly completed the function of collecting the 3-D point cloud data of the grain surface, and it consisted of the 3-D laser scanner (GSLS003, Hangzhou, China), the infrared camera of fixed waterproof lens (CBP-350N5, Upland, USA) and the workstation DELL M6800. The processing software system mainly realized the functions of point cloud data post-processing, data transmission and preservation. The software system comprised of the scanner control software, the grain volume calculation software and the reserved interfaces. In order to solve the problem of the rapid and high precision monitoring of the grain storage, the verification test of this system was carried out in a state-owed granary in Anhui province in February, 2014. In the test, the center of the 3-D laser scanner was fixed on the granary roof. All the instruments of the system were plugged into a power supply. After that, the upper computer could access to the local area network in order to control the whole system. The point cloud data of the grain surface, the grain volume and weight were obtained. The self-developed 3-D laser scanner of upside-down type for grain was used to scan the grain surface to get the point cloud data. Firstly, the scanner was connected by communicating with the upper computer. After that, the scanning parameters were initialized by zero adjustment function and the motor speed was set to start the scanning by the speed control function. Finally the 3-D point cloud data collected by the scanner were transmitted and stored in the terminal workstation. The upper computer was applied to communicate with scanner, collect point cloud data and control the working process of the scanner in the process of scanning. Then the grain volume calculation software was utilized to calculate grain storage volume and weight in time. First of all, the 3-D point cloud data of the grain surface was simplified, denoised and fused by the preprocessing function of the grain volume calculation software. Then the grain volume was calculated by the software, at the same time the grain weight was gained by setting the grain density in the parameter control function. In the end, the calculation results could be displayed on the screen of the workstation. The system worked in a stable condition in the test, finally eight groups of point cloud data were gained by scanning at the best rotational speed. The actual grain volume value was 8300.8 m3, which was provided by the state-owed granary. And the volumetric measurements of eight test groups were calculated in time by the grain volume calculation software. Through calculation, it was shown that the measured grain volume, which was monitored by the system based on 3-D laser scanning technology developed in this study, could meet the technical index of the maximum error less than 1%. And after a lot of tests, it was proven that this upgraded system was characterized by good stability, high measuring accuracy, and easy operation, therefore, the system promised as a higher precision and efficiency technique for monitoring grain volume in granaries. The effective implementation of this system will serve as a new method to access grain volume information based on 3-D laser scanning technology and data analysis method.