Aimed at the problem of leakage of an aviation hydraulic brake under low temperature environment,a low temperature screening test was designed to study the influence of sealing surface evaluation parameter (arithmetic mean deviation of surface profile Ra,maximum peak value of contour Rp and maximum height of surface profile Rz) on the low temperature sealing performance.The results show that the sealing surface constrained by traditional Ra indicator cannot fully meet the sealing requirement of hydraulic brake under low temperature environment.Rz and Rp indexes can better characterize and constrain the surface processing quality of sealing structures,and the surface constrained by Rz indicator can significantly improve the sealing performance of hydraulic brake.According the statistical results of experiment,the design reference value of Rz≤1.0 μm for sealing surface of hydraulic brake is given,and this reference value can be applied to the design of other similar aviation hydraulic products.