Abstract: The objective of this study was to investigate the difference and correlation between 4 mM lactate threshold calculated with interpolation method(P4-int) and exponential method(P4-exp).79 sets data of lactate and power from step tests in rowing were selected,and calculated with interpolation method and exponential method,respectively.It was found that there was no significant difference between P4-int and P4-exp.The linear regression functions for P4-int(x) and P4-exp(y) from the selected data were:y=0.983x + 6.4885(n=38,r=0.978,heavyweight men),y=1.0138x-0.2885(n=20,r=0.988,lightweight men),y=1.1042x-17.63(n=8,r=0.998,heavyweight women),y=0.9904x+3.64(n=13,r=0.990,lightweight women),y=0.997x+2.9208(n=79,r=0.998,all).It was concluded that 4 mM lactate threshold calculated with interpolation method and exponential method were comparable.Recommendation was given that one certain method of calculating 4 mM lactate threshold should be fixed during the longitude monitoring and diagnostics of aerobic capacity in long-term training.