FRP pultruded profile cracks, including appearance and inner crack. It can appear in any goods and any moment. The reason is mainly because of the crack onset exothermic shorter episodes of heat stress. There are many manufacturers who also agreed on this point. But at present domestic but also difficult to find a better way to eliminate thermal stress. Although the appropriate adjustment of mold temperature and pulling speed can temporarily gentle this question, as environmental conditions change and some unknown reason, the crack will reappear. Cracks sometimes suddenly appear in very normal circumstances that would make you impossible to guard against. Just add a few (the amount of resin 2%-5%), that have a significant effect. Because the amount is not added, the influence on the functionality of the product is very small, to enhance the effect of certain functions can. In addition, to reduce cracking, it also has to add product appearance luster, make the finished color more uniform strengths. This component in the formulation, can reduce the reject rate to a great extent, make the production more smooth. DP anti-cracking brightening powder to avoid cracking mechanism of finished products as follows: because it does not dissolve in the resin, so when it is slack in the resin, resin composition in successive phase size is about lax chondrules 50 – 100 m, in these chondrules and lax in a liquid resin minority. When the resin is heated, the successive phases and phases are to attack the swell and lax. In the heat to 120-140%, the crosslinked resin curing and shorten the beginning episodes, resin and lax phase chondrules within also attack curing. But now the slack phase pellets still follow the temperature increases continue to swell. Thus in the slack phase chondrules and one phase at the interface of stress and strain. As the temperature continues to rise, the successive phase crosslinking continues to attack and tends to end, along with the successive phase to shorten this process. So at the interface of stress and strain more. When the stress and strain to a certain level, slack phases spherules within the crosslinked resin network attack the micro crack and expansion in the chondrules within so that the stress and strain in jail at the interface. Through such a mechanism, to avoid the crack appears successively finished main skeleton network.