A communication transmitting module with a rigid light pipe, the communication transmitting module has thereon a protrusion with a pair of recesses near its bottom, and has on its bottom side an engaging block with a bevel surface. The rigid light pipe in the shape of "L" includes an upper and a lower portion, the upper portion is formed thereon an engaging hole for extending therethrough of the protrusion of the communication transmitting module, the engaging hole is formed near it a raised portion engageable in the recesses of the communication transmitting module; and the bottom of the lower portion provided with LEDs has a hook extendible from the bevel surface on the bottom side of the communication transmitting module to engage in the engaging block. The present invention can be easily and firmly assembled.