To obtain hydrogels with tough and self-healing properties, Ca
2+/Agar-Polyacrylic acid(Ca
2+/Agar-PAAc), Al
3+/Agar-PAAc, Fe
3+/Agar-PAAc composite double network hydrogels reinforced by ionic iron Ca
2+, Al
3+, Fe
3+ cations were prepared by "one-pot" method. The enhancement function of metal ions Ca
2+, Al
3+, Fe
3+, self-repairing properties, self-healing properties of reinforced hydrogels were studied. The tensile strength 320.7 kPa and elongation at break 1 130% of Fe
3+/Agar-PAAc double network(DN) gels are 12 times and 9 times respectively those of Ca
2+/Agar-PAAc DN gels. The tensile strength 320.7 kPa of Fe
3+/Agar-PAAc DN gels is 5 times as large as that of Al
3+/Agar-PAAc DN gels, elongation ratios of them are the same. Tensile with certain stain was applied to the sample to obtain damaged samples. The mechanical properties of Fe
3+/Agar-PAAc DN hydrogels can be recovered to 100% of initial state after being soaked in ferric ion solution for 30 min. The mechanical properties of Fe
3+/Agar-PAAc DN hydrogels can be recovered to 100% of initial state after being put in 50℃ condition for 15 min. By simply placing two hydrogel portions together and allowing enough self-healing time(48 h) for physical interactions to reestablish the network at the interface, the healed Fe
3+/Agar-PAAc DN hydrogels can be stretched to 800% of initial length. The Fe
3+/Agar-PAAc DN hydrogels reinforced by Fe
3+ possess excellent mechanical properties and self-healing properties, without adding any chemicals and external stimuli, both networks possess self-healing properties.