Abstract: Based on the model of heat and mass transfer with variable physical parameters, distribution of supersaturation from two creating methods was calculated in the two-section growth tube. Two methods are saturated air at low temperature with warmer water then meeting with colder water（method 1） and saturated air at high temperature with colder water then meeting with warmer water（method 2）. Features of supersaturated environment formed from different methods were analyzed. The results demonstrate that methods of creating supersaturation and temperature differences are considered when choosing the optimum length of first and second section of two-section tube. Compared with one-section tube, supersaturation is higher in the two-section tube and has a significant improvement from method 1. The increase of inlet flow rate and pressure is positive to promote supersaturation from method 1 and has a little growth from method 2 but supersaturation reduces when inlet flow rate and pressure is high.