This paper takes the complex mining conditions of Shendong mining area as the research object, and conducts in-depth research on the special rules of mining pressure manifestation under the goaf and the coal pillars of the section. The static load model and dynamic load model of the mining face under the coal pillars of the section were constructed. The stress calculation method of the upper coal and lower coal was derived in the static load model. In the dynamic load model, the additional load caused by the collapse of the basic top rock block of the upper coal due to the mining damage and coal pillar instability was calculated, and the influence of entering and leaving the section coal pillar on the hydraulic support force was analyzed. Based on the geological and mining conditions of the X working face of a coal mine in Shendong, a numerical simulation model was established to simulate the variation law of the coal roof pressure when the mining face entered and exited the coal pillars. By analyzing the monitoring data of the roof stress 5-10 meters in front of the coal wall, the conclusion was drawn that the stress increase of the out-coal pillar was more than 10% higher than that of the in-coal pillar. This conclusion not only verifies the rationality of the dynamic load model derivation but also provides a basis for the selection of dynamic load coefficients for entering and exiting coal pillars. The B coal pillar area that the X working face of the Shendong mine is about to pass through is treated with hydraulic fracturing and unloading measures to soften the rock layers and reduce pressure. The field measurement data shows that the resistance of the hydraulic support when entering and exiting the B coal pillar is reduced from 22333 kN in the A coal pillar area to 19616 kN, and the step distance of the periodic support is reduced from 21.7 meters to 18.28 meters, effectively alleviating the influence of pressure changes in the entering and exiting section coal pillars on the hydraulic support state. The research results of this paper have certain reference and reference value for coal mining under similar or similar conditions.