The present invention is to provide a harmonic spurious signal suppression filter, which comprises microstrip lines disposed on a printed circuit board of a wireless network product, wherein one end of a microstrip input end is perpendicularly connected to one end of a first microstrip line, one end of a microstrip output end is perpendicularly connected to one end of a fourth microstrip line, the first and fourth microstrip lines are interwovenly arranged in an interdigital finger form, a second microstrip line is extended from both the microstrip input and output ends, and each end of the second microstrip line corresponding to the location of the first and fourth microstrip lines is connected to a third microstrip line of a meandering shape.