Abstract: The step horizontal well completion system is employed to carry out the production of complex reservoirs. The completion technology has two requirements: firstly, step cementing of the water/oil bed; secondly, step screen completion. However, the commonly used ECP can not be applied to the selective horizontal well completion. Through improving the packer structure, using the differential sizing collar and the automatic cementing one-way valve, adjusting different pressure, special completion and cementing is fulfilled. Field application shows that the full rubber ECP meets the requirement of selective completion and multi-way production and solves the problem of the cement pollution in undersaturated reservoirs at the bottom of the step horizontal well completion and the screen cementing. The selection and improvement of the casing tools is favorable for improving the screen top cementing technologies.