Abstract: The existing oil viscosity reducing technique used in Tahe Oilfield takes thin oil and heavy oil through one inlet where both states interfere with each other.The interference may result in uneven mixing and lead to tubing blocking.In view of the above-mentioned problem,a kind of shunting dilute mixer that separates a thin oil suction inlet from a heavy oil suction inlet was designed.By referring to previous evaluation method of the mixing effect,a numerical simulation method was used to analyze influence of the pore aperture,the tapping layers and the tapping angle of the thin oil suction inlet on the mixing effect.Based on simulation results,the structural parameters of the shunting dilute mixer were optimized to the setting of 8.0 mm optimum aperture of thin oil suction inlet,arranged in 4 layers along the axial direction,with a tapping angle of 33°.The lab test results on the performance of the designed shunting dilute mixer showed that it had a high mixing uniformity after thin oil and heavy oil passed through the shunting dilute mixer.Therefore,the shunting dilute mixer could improve the mixing uniformity of thin oil and heavy oil,and solve the problem of tubing blocking caused by the non-uniform mixing of thin oil and heavy oil.