A method of forming thin film solar cell includes the following steps. A substrate is provided, and a plurality of first electrodes are formed on the substrate. A printing process is performed to print a light-absorbing material on the substrate and the first electrodes to form a plurality of light-absorbing patterns. Each of the light-absorbing patterns corresponds to two adjacent first electrodes, partially covers the two adjacent first electrodes, and partially exposes the two adjacent first electrodes. A plurality of second electrodes are formed on the light-absorbing patterns.