A miniaturized tri-band Long Term Evolution(LTE) microstrip antenna based on the Composite Right/Left-Handed Transmission Line(CRLH) theory is studied. The microstrip antenna is miniaturized by using the zero-order resonance characteristic of CRLH. The simulation results show that the three operating frequency bands of the microstrip antenna are: 1?840-1?860?MHz, 2?130-2?160?MHz, 2?620-2?660?MHz. The Band3, Band4, and Band7 of the Frequency Division Duplexing(FDD) LTE plan are accurately covered. The electrical length is 0.17λ. Finally, the microstrip antenna is processed and measured to verify the accuracy and effectiveness of the simulation. The multi-frequency miniaturized antenna can not only save the antenna feed resources of the base station greatly, but also cut the cost of base station construction effectively.