A design method for composite right/lefthanded transmission line（CRLHTL）unit cell based on a lattice topology is proposed in this paper. Based on the theory of CRLHTL and combing with the equivalent circuit of a lattice topology, the Bloch impedance and Bloch propagation constant are analyzed, and the microstripline structure with threelayer dielectricslab is constructed using the electromagnetic simulation software for physical implementation. The simulation results show that the bandwidth of lattice structure of CRLHTL is 20.2 GHz, with insertion loss below 0.5 dB and return loss greater than 10 dB. The center frequency is 6 GHz when the phase shift of the transmission line is zero. Thus the CRLHTL cell based on a lattice topology is proved not only compact, but also has good performance.