Background:
As WHO FCTC took effect in China, more and more cities have legislated or amended laws against smoking in public places. There still existed many kinds of barriers and problems about the law enforcement. This study focused on the activities took by enforcers and owners of places to evaluate situations that influence the effect of laws and regulations against SHS.

Methods:
This study combines methods of interviews and field observation. Study of compliance of net bars: 20 net bars at each city were observed.84 observations were accomplished. Invited 15 officers, 30 enforcers and 14 owners of net bar. Focus group and in-depth interviews were conducted at five cities.

Results:

1. Smoking behaviors were found in 69 net bars, attendants from only 2 bars discouraged smokers but failed. Smoking ban in bars didn't improve no-smoking environments in the bars.
2. City supervision and enforcement environments need to be improved. Comprehensive and partial smoke-free, penalty process and amounts bring about barriers in enforcement activities. The enforcement coordination mechanism and enforcement pattern is limited by authority, function, initiative and focus of enforcers.
3. Various factors influenced owners to take responsibility in the enforcement of law, et al, afraid of losing customers and incomes for owners; Lack of knowledge of hazards of SHS.

Conclusions:
Not all of the net bars comply with the law. Power of the coordination, initiation and knowledge of hazards of SHS of the enforcers, all of these influence power of enforcement of net bars. Failure of creating social atmosphere of smoking ban before and after the law impairs effect of enforcement of the law.
Recommendation: Amending the law to achieve a comprehensive smoke in the indoor public places and develop a detailed enforcement guideline; building effective supervision mechanism, and mobilizing initiation of the enforcers; completing social supervision mechanism and motivating the public.