Abstract: This review summarizes eight kinds of Ziegler-Natta catalysts for Unipol gas-phase process of polyethylene production together with the analysis of their advantages and disadvantages. M catalyst is widely applied，while its catalytic activity is low. BCG-IV catalyst shows high initial and total activities for the addition of accelerator during catalyst preparation. SCG-1 catalyst has moderate activity，while its preparation is simple. GM catalyst has high catalytic activity and the polymer produced has high bulk density owing to the introduction of special electron donor during the activiting process of carriers. However，J catalyst is the leading direction of Unipol process catalyst development for its outstanding performance. BCS-02 is more suitable for condensated state operation. Preparation of BCS-01 catalyst is unique，while requires demanding preparation conditions. SLC catalyst，without the application of silica gel carriers，shows high catalytic efficiency with greatly reduced production cost. Some suggestions to promote the development and localization of Unipol process catalysts are proposed.