In order to facilitate the safe and efficient use of saline water for irrigation, it is necessary that the effects of saline water irrigation on crops and soil safety should be understood. A three-year (2003～2005) field experiment was carried out to investigate the effects of saline water and soil matric potential (SMP) on tomato growth and yield under drip irrigation in semi-humid regions of North China. The experiment results indicated that there are no obvious effects on tomato root dry weight density, root length density, maximum leaf area index (LAImax), total leaf chlorophyll content and yield with the increasing of electrical conductivity of saline water (ECi) from 1.1 dS/m to 4.9 dS/m when the SMP at 0.2 m depth immediately under drip emitters was controlled from﹣10 kPa to﹣50 kPa. Furthermore, the ECi and SMP treatments have no interactive effects on tomato growth and yield. So, in semi-humid regions of North China, saline water with EC value less than 5 dS/m can be used to irrigate tomato after seedlings survival stage by drip irrigation, and the saline water is safe to tomato growth and yield.