A music box of a play bed includes a box member used for playing music, and a toy hanger, on which several toys are hung for a small child to play in the play bed; the box member has two fitting holes as well as a fitting cavity on an upper side; hooks are respectively detachably connected with the fitting holes so that the box member can be hung on two adjacent upper horizontal rod parts of the bed frame; various types of hooks are available for suiting various types of bed frames whose rod parts have different shapes; the toy hanger is detachably connected with the fitting cavity at a lower end, and can fold such that it can be removed from the box member, and folded to occupy less space when it is not use.