An outer frame drainage structure of a concentrator type solar cell module, wherein, a drainage element having a predetermined height is disposed between a side board and a frame edge, hereby keeping a drainage slit between said side board and the corresponding frame edge, so that moisture will not remain inside the concentrator type solar cell module, thus the concentrator type solar cell module is able to operate in an optimal light-to-electricity conversion efficiency. In a structure mentioned above, a concave slit is formed through engaging and positioning an extended and bent positioning portion of the side board into a positioning slot of the frame edge, and the concave slit is linked to the drainage slit, thus facilitating exit of moisture and preventing intrusion of foreign objects effectively.