In this article, a new type of microchip with filmy channels and-a sample-injection fracture is introduced. Unlike commercial microchip, new microchip possessed filmy channel with width 2-3 mm. The effective cooling ability made filmy channel microchip restrain the,generation of joule heat even under electric field of 588 V/cm. Moreover, wider channel could be more easily modified to prevent the absorption of samples, load more samples and result in a higher sensitivity. Sample-injection fracture was first applied to match the filmy channel in microchip. Equipped with an amperometric detector, the characteristics of the newly designed filmy channel microchip had been studied and the results showed that it had good reproducibility, higher sensitivity and excellent separation ability. The microchip was also applied to separate L-tryptophan's metabolites, namely 5-hydroxy-L-tryptophan, 5-hydroxytryptamine and 5-hydroxy-indole-3-acetic acid.