Based on experiments by using the methods of weighing soil moisture through drying and neutron probe, the soil drought condition was diagnosed for the cotton which was irrigated respectively with drip irrigation under mulch and furrow irrigation. By using two selected indexes of drought diagnosis, the soil moisture content suitable for growing crop and the crop water stress index (CWSI) were evaluated. According to the experiments and analyses, it is revealed that the soil moisture conditions required by the growing cotton, do not change with the irrigation techniques. In its high water demand period, the cotton, whether it was irrigated with drip irrigation under mulch or with furrow one, has almost identical index for drought diagnosis. Due to its poor drought tolerance and its high drought danger, however, the cotton irrigated with the drip irrigation under mulch should be given more water for the drought diagnosis compared with the one irrigated with furrow technique when the irrigation scheme decision is made for the cotton.