This study numerically investigated the condensation heat transfer and flow characteristics of refrigerants R134a in rectangular minichannels. Three-dimensional simulations were carried out at different mass flux values, vapor qualities and gravity conditions through using the VOF model, the turbulence model and the phase transition model. The effects of various parameters on the surface heat transfer coefficient and the friction pressure gradient is clarified. The condensation process is found to be enhanced due to the increase of vapor quality and mass flow, while the friction pressure gradient decreases with the decrease of vapor quality and mass flow. According to the data obtained from the simulation, the liquid film tends to accumulate along the corner of the cross section in retangular minichannel. And the thickness of liquid film increased with the decrease of mass flux and vapor quality.