Abstract:The allowable rebound deflection is main criteria for pavement design offorest highway. The peper analyses the each coefficient and calculated formulaof the allowable rebound deflection. Based on results surveying highway andtest ug data at home and abroad, and thinking over the conditions of foresthighway the author puts forward a suggestion value of grade coefficient ofhighway to calculate the allowable rebound deflection. It is also carried on asolution of pavement thickness calculation with the suggested grade coefficient.This article showed that it is possible to achieve a larger reliability for desig-ning forest highway with the suggested coefficient.