Load-sensitive hydraulic system, warm-up control method and engineering machinery

The invention discloses a load-sensitive hydraulic system, a warming-up control method and engineering machinery. The hydraulic system comprises a controller, a heating valve group and a temperature detector used for detecting the temperature of hydraulic oil. The heating valve set comprises an unloading valve and an electric proportional valve used for controlling the opening degree of a valve opening of the unloading valve. An oil inlet and an oil outlet of the unloading valve are correspondingly communicated with an EF port of the priority valve and an oil tank loop; an oil inlet of the electric proportional valve is connected with a pilot oil source; a first overflow valve arranged between an LS control cavity of the priority valve and the oil tank loop is an electric proportional overflow valve; and the controller is used for controlling the output pressure of the electric proportional valve to open the unloading valve during warming-up, and controlling the overflow opening pressure of the first overflow