Analysis on the quality data collected by traffic quality supervision department shows that most of Hainan Province part project quality level is lower than the national average.Especially in bridge engineering quality sampling qualified rate is not high and volatile, and some sub project quality indicators also have significant gaps.The result, that was gotten by using questionnaires survey and linear stepwise regression analysis, show that the main factors of influencing the highway engineering quality in the province include that monitoring of engineering entity and input factors,improvement of quality supervision system and network,perfection of quality incentive and restraint mechanism etc.The questionnaires survey and interviews investigation show the lack of balance mechanism among the owner,construction,supervision units,the lack of quality assurance system of construction units and the lack of effective social supervision channel.Therefore, some methods were proposed which include construction of "3+2+1" highway quality supervision balance and coordination architecture system,opening and standardization of supervision and test market,perfection of marginal quality incentive and restraint mechanism taking contractors and employees as the core,improvement of quality assurance and supervision system in construction unit,guiding of the social forces to supervise.