To investigate the effects of polyethylene glycol cross-linking on the mechanical properties, 80 porcine aortic valves were harvested, decellularized, and introduced with sulfhydryl. Then the valves were randomly assigned into 5 experimental groups and 1 control group(n=16). For the valves in those experimental groups, branched polyethylene glycol diacrylate(PEG) of 5 different molecular weights(3.4, 8, 12, 20, 40 k Da) were synthesized and cross-linked with them respectively. The efficiency of the cross-linking was determined by measuring the amount of residual thiol group and the mechanical properties of the cross-linked valve leaflets were assessed by uni-axial planar tensile testing. The efficiency of the PEG 20 k Da group was 70.72±2.33%, obviously superior to that of the other groups(p<0.05). Tensile test proved that branched PEG cross-linking can significantly enhance the mechanical behaviors of the decellularized valve leaflet and the Young’s modulus of each group was positively correlated with the molecular weight of PEG. It was concluded that branched PEG with the molecular weight of 20 k Da can effectively cross-link the decellularized porcine aortic valves and improve their mechanical properties, which makes it a promising cross-linker that can be used in the modification of decellularized tissue engineering valves. To investigate the effects of polyethylene glycol cross-linking on the mechanical properties, 80 porcine aortic valves were harvested, decellularized, and introduced with sulfhydryl. Then the valves were randomly assigned 5 experimental groups and 1 control group (n = 16). For the valves in those experimental groups, branched polyethylene glycol diacrylate (PEG) of 5 different molecular weights (3.4, 8, 12, 20, 40 kDa) were synthesized and cross-linked with them respectively. The efficiency of the cross-linking was determined by measuring the amount of residual thiol group and the mechanical properties of the cross-linked valve leaflets were assessed by uni-axial planar tensile testing. The efficiency of the PEG 20 k Da group was 70.72 ± 2.33%, obviously superior to that of the other groups (p <0.05). Tensile test proved that branched PEG cross-linking can significantly enhance the mechanical behaviors of the decellularized valve leaflet and the Young’s modulus of each group was positive It was concluded that branched PEG with the molecular weight of 20 k Da can effectively cross-link the decellularized porcine aortic valves and improve their mechanical properties, which makes it a promising cross-linker that can be used in the modification of decellularized tissue engineering valves.