Abstract: A paintball gun loading device includes a main body, a tightening ring and a retaining ring. The main body has a first clamping section and a second clamping section. The first clamping section comprises a first inclined surface and the second clamping section comprises a second inclined surface. The tightening ring comprises a third inclined surface and a fourth inclined surface. The third inclined surface is engaged with the first inclined surface of the first clamping section, while the fourth inclined surface corresponds to a fifth inclined surface of the retaining ring. The retaining ring further comprises a sixth inclined surface corresponding to the second inclined surface of the second clamping section. This tightness of the retaining ring does not apply to the main body direct. There is no deformation concern of the main body.