Based on the theory of parallel mechanism, a 3-DOF mechanism which was completely decoupled was chosen as the main part of the tea sieving machine to solve the problem that the traditional tea sieving machines can not complete multi-dimensional vibration. D-H matrix was applied to calculate the forward and reverse solution of the position, and the orthogonal experiment was used to test the screening performance. The test shows that the 3-D vibration makes the tea spread fast in the screen surface, short the time by nearly 20 times and get a better screening performance.