This thesis discusses what effect resulted by jitter and skew in transmission quality of high speed serial circuit. In this thesis, we use statistical method to build a circuit model based on USB 2.0 circuit. Use this to discuss jitter and skew what will result in transmission quality of USB 2.0 circuit. Advanced discuss different components of time error will cause what effect. Aside from this, this thesis also uses Bit Error Rate Test method to verify the viability of TQ function.