This paper proposes a lattice-shaped micro catheter actuated by hydraulic pressure. This catheter is supposed to alleviate the difﬁculty of inserting the catheter into narrow and branched blood vessels. The lattice structure of the body of the catheter is exploited to make bending motion. An analytical model is developed to compute deﬂection of catheter considering the coupling effect of the shape. Static analysis is conducted to optimize the design parameter of the structure for maximum deﬂection. Simulation results show that the proposed catheter with diameter of 1mm and 40mm length can bend 29mm maximum.