Series of polyacrylamide hydrogels with high mechanical strength were synthesized using hydrophilic reactive microgels (HRM) with C=C double bonds as crosslinkers. The hydrophilic microgels were prepared by inverse emulsion photopolymerization and then were chemical modified by N-methylolacrylamide (NMA) to obtain HRM. Chemical-modifying conditions affecting the HRM double bound content were investigated. The maximum double-bond content was 1.82% at the optimum conditions of NMA 8 g, hydrochloric acid 0.8 mL, reaction temperature 60 degrees C, and time 4 h. The mechanical properties of the hydrogels were significantly enhanced by using HRM as crosslinkers instead of the conventional crosslinkers. These HRM hydrogels were studied by varying such parameters as HRM content, monomer concentration, HRM double- bond content, and the initiator dosage. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2594-2603, 2011