Abstract: Experiments were done to examine the effects of geometric and operational parameters on the hydraulic resistance of throttle set,and the experimental parameters were as follows: flow rate ranged from 1.5 to 33 kg/h,inlet fluid temperature from 20 to 70℃,and pressure from 1.8 to 2.4 Mpa,respectively.An empirical equation for hydraulic resistance was obtained after the effects of pitch number of throttles,throat diameter,temperature,pressure,flow rate and outside heat source on the hydraulic resistance of throttle set were examined.The results indicated that the pitch number,throat diameter,flow rate and temperature has great effect on the resistance of throttle set;when the inlet temperature was constant,the effect of external heat flux on the resistance was considerable;the higher the heating power was,the higher the temperature rise between inlet and outlet was,and the less the resistance was.