A self-charging device for mobile robots, which includes a charging cradle and a charging pin, the charging cradle includes a charging contact and a first elastic member connected with the charging contact. The charging pin is used to contact the charging contact for charging. Preferably, the charging cradle also includes a buffering block, a second elastic member and a mounting enclosure. The charging contact is connected with the buffering block through the first elastic member. The buffering block is provided encircling inside the mounting enclosure. One end of the second elastic member is connected with the buffering block, and the other end is connected with the mounting enclosure. The self-charging device for mobile robots is capable of counteracting the deviation angle due to the misalignment when the mobile robot is charging, and buffering the impact force produced when the charging contact docks with the charging pin.