A new synthetic strategy for high-flow nylon 6 was developed in this article. Generation 1, 2, 3 (G1, G2, G3) polyamidoamine (PAMAM) dendrimers reacted with p-phthalic acid by equimolar terminal groups in water solution, respectively, and mother salt solution was then prepared. The high-flow nylon 6 was prepared with suitable quantity of mother salt solution, end-capping agent, and z-caprolactam by in situ polymerization. Blue shifts are found for the peaks of NH (gamma N-H and 2 delta N-H) of the high-flow nylon 6 compared with pure nylon 6 in the IR spectra. Comparing with the pure nylon 6, the high-flow nylon 6 containing low content of PAMAM units, has high-flow property and almost the same mechanical property. The high-flow nylon 6 with low content of PAMAM units has greater melt-flow index (MFI) (the value of MFI increased by 70-90%). Hardly any decrease in the tensile strength is observed with the elongation at break decreasing by 20-35%. But the izod impact strength of the high-flow nylon 6 increases. The SEM images show that the high-flow nylon 6 presents brittle fracture with conglomeration-like structure, while pure nylon 6 exhibits plastic fracture with island-like structure. DSC thermograms of nonisothermal crystallization exhibit that the peak of high-flow nylon 6 broadens compared with pure nylon 6, and the broader peak means the wider processing temperature. (C) 2008 Wiley Periodicals, Inc.