A slipknot polymer network model based upon the fuzzy constraint method is put forward in this paper.The local concentrated entanglement effects are quantitatively manifested by introducing the constraint tensor and membership function
and a random tetrahedral slipknot cell is chosen as the average representative unit of the network structure.By making use of the theory of fuzzy probability and statistical mechanics
the expression for the free energy of deformation is obtained
which can be simplified to the formula given by Ball-Edwards'slipknot network model.