This study establishes an assembly model for composite/aluminum alloy multi-bolt joint structures and investigates the preload distribution patterns of the bolts under four tightening sequences: Sequential tightening, staggered tightening, tightening from the middle to the ends, and tightening from the ends to the middle. It focuses on three assembly conditions: No assembly gap, forced assembly with a gap, and gap compensation with shims. By combining experimental and finite element methods, the preload distribution patterns under the aforementioned tightening sequences were analyzed. The results show that in cases involving an assembly gap, the bolt preload variation increases as the assembly gap expands. Among the four tightening sequences, when adopting the sequence of tightening from the ends to the middle, the preload distribution exhibits better consistency, and the final preload of each bolt is closer to the target preload.