The Structure and simulation of a wideband, high efficiency 0.14THz Schottky varactors frequency doubler have been presented. The doubler is based on quartz microstrip circuit integrated in waveguide cavity, in which wire bonding is used to get diode grounded and apply external DC bias properly and wideband electromagnetic coupling structures are also designed for various sections of frequency doubler. Based on the analysis of modeling and impedance of Schottky varactors, the optimal doubler design have been accomplished by combining the three-dimensional finite element calculator with nonlinear harmonic balance tool. The simulation results shows: at the 65 ∼ 75GHz driving frequency and 20dBm driving power, the maximum output power of frequency doubler is 10dBm with efficiency up to 10.8 %.