In order to explore the influence of the interaction between the laying length of drip irrigation belt and inlet pressure on the irrigation uniformity, three J-type (imported) drip irrigation belts and one G-type (made in China) drip irrigation belt were laid for the study of drip flow under different laying lengths and inlet pressure combinations. Then, the indices of Christiansen uniformity coefficient (Cu), variation coefficient (Cv) and Keller uniformity coefficient (Eu) were used to evaluate the drip irrigation belts. Experimental results show that Cv, Cu and Eu all change with the inlet pressure and laying length, Cu is positively correlated with Eu , but negatively correlated with Cv. With Cv as the discrimination index, when the laying length is 200 m, the inlet pressure of J1-type ranges from 5 to 11 m, and that of J2-type ranges from 3 to 11 m, the quality of the drip irrigation belt can reach A (excellent); the quality of J3-type is B (good) and G-type is D (unqualified) when the inlet pressure fall in the range of 1-11 m. When the laying length is 100 m, the quality of J-type drip irrigation belt is A (excellent) under the inlet pressure of 1-11 m; G-type is C (general) under the inlet pressure of 1-3 m. With the uniformity coefficient Eu and Cu as the discriminant indices, the irrigation uniformity of J-type drip irrigation belt is the lowest when the laying length is 300 m, and it is the highest when the inlet pressure is 9-11 m. Based on the above criteria, the optimal combination of laying length and inlet pressure of different drip irrigation belts are as follows: the length is 200 m, the inlet pressure is 9 m for J1-type drip irrigation belt; the length is 200 m, the inlet pressure is 11 m for J2-type and J3-type drip irrigation belt; the length is 100 m, the inlet pressure is 7 m for G-type drip irrigation belt.