Laser diffraction method(LD method) has been regarded as an effective method of measuring soil particle size distribution( PSD) in recent years. In order to compare PSD difference in measurements by LD method and pipette method in black soil region

178 soil samples collected from various layers of 36 soil profiles were analyzed by LD method and traditional pipette method. Results showed that，compared with pipette method，clay content by LD method was under-estimated by 19. 69 0 o，and silt and sand contents were overestimated by 14. 66%and 5. 13%，respectively. According to US soil texture classification

soil texture varied from silt and clay texture to sand and silt texture

compared with pipette method. For clay，silt and sand particles

three PSD transform models between LD method and pipette method were built. When the transform models were used to revise PSD by LD method

the accuracy of measured PSD was 96. 97%~98. 71%and the accuracy of determined soil texture classification reached 83. 15%by LD.