Although urban management staff (Chengguan, the para-police in China) violence toward street vendors has been widely reported in China but how the violence is socially produced is under-studied. With the data collected from participant observation, systematic social observation, interviews with Chengguan and street vendors and content analysis of newspaper reports in Guangzhou, this research finds that most of violence towards vendors is conducted by Chengguan assistants: the socalled temporary staff. While the official discourse attributes the occurrence of violence to the low quality of Chengguan assistants, we argue that such claims tend to individualize social problem and blame the weak. This research reveals that the reason why most of violence towards street vendors is conducted by Chengguan assistants lies in the unequal division of labor resulted from unequal power structure between official Chengguan and Chengguan assistants. While Chengguan assistants are overwhelming forces of street law enforcement, the official Chengguan tend to stay away from the street. The convergence of likely offenders (Chengguan assistants) and suitable targets (vendors) on the street naturally leads to the possible violence occur between them. We further disclose that when official Chengguan do appear on the street, it becomes a contributing instead of a containing factor of violence as they tend to give orders to Chengguan assistants and the latter feel backed and pressured with institutional power, and therefore are more likely to use violence in law enforcement. This research contributes to an understanding of how Chengguan violence occurs in China. It also contributes to an understanding of why violence tends to occur within the underclass as both Chengguan assistants and street vendors belong to the urban poor