The invention provides a Dengue fever prevention and control method and system. The method comprises steps of acquiring multiple monitoring places in a mosquito eradication region and the mosquito density corresponding to each monitoring place, and screening out the monitoring place where the corresponding mosquito density in the mosquito eradication region is larger than the preset density threshold value so as to obtain a key mosquito eradication place in the mosquito eradication region; marking the mosquito eradication place on a map, and sending the marked map to a terminal of a drug spraying worker so as to guide the drug spraying worker to go to the mosquito eradication place to eradicate mosquitoes. According to the invention, drugs are mainly sprayed to a monitoring place with highmosquito density, so the mosquito eradication work is allowed to be quite targeted, the drug spraying efficiency and drug eradication effects are improved, quantitative estimation of the mosquito density monitoring and mosquito eradication work is achieved and working quality is improved.