The invention discloses an enhanced denitrification integrated treatment device for a high-ammonia nitrogen water body and a wastewater treatment method of the device. At present, the amount of industrial wastewater and the amount of domestic sewage are increased year by year, and the problem of water pollution is increasingly prominent. The enhanced denitrification integrated treatment device forthe high-ammonia nitrogen water body comprises a floating algae reaction unit, a multi-media biofilm filter layer unit and a microbial reaction unit sequentially from top to bottom, wherein the multi-media biofilm filter layer unit is divided into a filter tank and an overflow tank, the filter tank is provided with an algae inhibiting layer, a phosphorus removal adsorbent layer, a sandstone layerand a gravel layer sequentially from top to bottom, and the top of the inlet end of the multi-media biofilm filter layer unit is connected to the bottom of the water outlet end of the floating algaereaction unit; and the bottom of the overflow tank communicates with the bottom of the water inlet end of the microbial reaction unit. The concentration of the nitrogen element in the wastewater can be reduced through biodegradation of algae, the treatment effect of the wastewater is improved, and inhibition of high-concentration ammonia nitrogen to growth of microorganisms is avoided effectively.