In order to overcome the defects of narrow bandwidth, low efficiency and high cost of existing microstrip antennas, an X-band broadband and efficient stacked microstrip patch antenna is proposed on a low cost FR4 substrate. The antenna is composed of multilayer FR4 substrate stacks. Through the introduction of air cavity, the effective dielectric constant and dielectric loss of the antenna are reduced, and the efficiency and bandwidth of the antenna are improved. The use of parasitic patches increases the reflection zero in the band, which further enhances the bandwidth of the antenna. At the same time, in order to compensate the parasitic inductance of the feed probe, the input impedance of the antenna is matched by microstrip line. Simulation and experimental results show that the frequency range of input VSWR less than 2.0 is 7.8~11.6GHz, and the relative bandwidth is 40 %. The antenna gain is 7.6dBi and the efficiency is 83%. Compared with the traditional microstrip patch antenna, it has the characteristics of broadband, high efficiency and low cost, and has broad application prospects.