The invention discloses a lithium battery thin film thickness and surface defect detection device and method based on a conveying belt. The device comprises a frame, a first desktop, a computer, a lower computer, a lithium battery thin film conveying device, a CCD camera defect detection device, a C-shaped scanning detection device, a second desktop, a tank chain and a box body inner side. The lower compute, the computer, the lithium battery film conveying device and the CCD camera defect detection device are placed above the first desktop; The C-shaped scanning detection device is arranged onthe second desktop, and a bead screw rod guide rail sliding table is arranged outside the second desktop. A stepping motor is arranged at one end, and a rolling bearing is arranged at the other end,wherein a supporting base is arranged on the periphery of the rolling bearing, and a sliding block is arranged on the lead screw. A C-shaped scanning detection mechanism is arranged at the upper end of the sliding block, and an upper laser sensor and a lower laser sensor are installed inside the front end. A two-dimensional micro-displacement adjusting mechanism is fixed inside the lower end of the C-shaped scanning detection mechanism. The device integrates intellectualization and mechatronics, and is high in function realizability and low in cost.