Abstract: A boundary sampling technique suitable for three-dimensional DSMC(direct simulation Monte Carlo) calculations was studied, which could be used to give proper entering particle parameters according to the inlet conditions. A new kind of boundary statistical technique was proposed, which could be taken to obtain macroscopic flow parameters just at the boundary interface, from the statistical data of the entering or escaping particles or the ones impinging on the wall. This new statistical technique makes up for the defective of traditional DSMC statistical technique, which can only get the inner flow field parameters, but can not get the interface parameters. This statistical technique is essentially a universal arithmetic, not just suitable for the DSMC method. A calculation of infinite far flow passing around a sphere was carried out. The results show that the sampling and statistical techniques are effective.