The annual production capacity of more than one million tons has been realized because Mahu conglomerate reservoirs are rich in oil and gas resources and a series of development technologies featuring“large well cluster，multi-layer system，small well spacing，long well section，staggered type，dense cutting，zippered type，and industrialization”have been formed under the guidance of the idea of geological engineering integration. However，the drilling and completion engineering and stable production are significantly affected due to the different degrees of inter-well interference in the process of three-dimensional development of horizontal wells with small well spacing and volume fracturing of horizontal wells. Therefore，theoretical research and numerical simulation are combined to study the fracturing interference mechanism and analyze the main control factors. The results show that ①according to the connection modes and characteristics of inter-well interference in horizontal well fracturing，the inter-well interference in horizontal well fracturing in Mahu conglomerate reservoirs can be divided into three types：fracturing interference caused by the development of natural weak structure，interference caused by fracture communication，and adjacent well interference induced by the connectivity of the pressure/stress interference zones due to the fracturing interference；②the horizontal well spacing is the key factor affecting the inter-well interference and the inter-well interference degree in horizontal well fracturing，the the prob‐ability of inter-well interference in the study area increases greatly when the spacing between horizontal wells is less than 300 m.Therefore，it is necessary to comprehensively consider the positive effect of fracturing interference on reservoir production and the adverse impact of fracturing interference on the drilling and completion engineering / the oil production and reasonably optimize the design of horizontal well spacing，which are of positive significance to the safe and efficient development of conglomerate reservoirs.