The　trust　evaluation　is　one　of　the　key　issues　that　need　to　be　resolved　in　credible　trust　management　for　trust-based　access　control　in　open　networks.　Referring　to　the　complexity　of　trust　relationships　in　human　society,　some　relevant　concepts　on　trust　and　proposes　a　dynamic　comprehensive　trust　evaluation　method　for　open　networks　was　introduced.　This　method　establishes　a　trust-based　access　control　framework　and　introduces　a　balanced　weight　factor　in　trust　evaluation　to　solve　the　problem　for　determining　the　weights　between　direct　trust　which　includes　historical　information　to　improve　accuracy　and　recommendation　trust　which　includes　the　bonus-penalty　factor　as　well　as　the　reliability　of　evaluation　to　improve　reliability　and　efficiency.　Experiment　shows　that　the　proposed　method　can　achieve　certain　robustness　and　better　dynamic　self-adaptability.　©,　2015,　Beijing　University　of　Posts　and　Telecommunications.　All　right　reserved.