Abstract: Rapid release and full use of internal waste dump space is an important way in surface coal mining to achieve safety,cost reduction,high efficiency and green mining. To solve the problem of arranging the working line of internal waste dump in cross exploitation and inner dumping,the internal waste dump is strengthened,and the relationship between the relevant factors such as the basement dip angle and the layout of the working line in stope and the arrangement of the working line of internal waste dump were studied. Taking into account the horizontal and inclined coal seams in surface coal mining,the 3 Dmine was used to construct the spatial geometric model of the stope,internal waste dump,the end slope and the basement under maximizing utilization conditions. Based on the engineering conditions for maximizing the utilization of internal waste dump space,the mathematical expression of arranging the working line of internal waste dump was derived,and the influence of the layout of the working line and the slope angle in stope,the slope angle of internal waste dump,and the basement dip on the layout of internal waste dump was theoretically revealed. This method was applied to surface coal mining. The results showed that the necessary and sufficient conditions in cross exploitation and inner dumping to maximize the utilization of internal waste dump space are as follows: the dip angle of the basement α is less than the slope angle βp of internal waste dump; the arrangement direction of the working line of internal waste dump θc which is negative correlation to the dip angle of the basement α and the slope angle βc of stope is positively correlated with the slope angle βp of internal waste dump and the layout of the working line in stope θc. In 2023 of the horizontal mining area of an open-pit coal mine,the working line direction of stope θc= 90° is planned,and the layout direction of the working line of internal waste dump θp= 46. 3° can be used to maximize the utilization of space. The results can be used to optimize the layout of the working line in the inner dump to make up for the large workload of the test drawing of the layout of the working line in common methods.