In order to meet the requirement in the prior art, achieve progressive reliable control of a single numerical control oil cylinder, and assist in achieving alignment and automatic posture adjustment control strategies of a guided missile loading system, the invention provides a method for conducting closed loop progressive control of a numerical control oil cylinder through a stepping motor and a displacement sensor. The stepping motor is connected with the numerical control oil cylinder and used for controlling the corner position of the numerical control oil cylinder and making a cylinder rod of the numerical control oil cylinder stretch out, wherein the cylinder rod of the numerical control oil cylinder is used in the method for conducting closed loop progressive control of the numerical control oil cylinder through the stepping motor and the displacement sensor. The displacement sensor is used for detecting the stretch-out length of the cylinder rod of the numerical control oil cylinder and outputting the stretch-out length as absolute displacement of the cylinder rod. The method includes the following steps that firstly, motion times and surplus distance of graded progressive motion are calculated; secondly, the cylinder rod of the numerical control oil cylinder is driven to move according to the motion times and the surplus distance; thirdly, halting is conducted.