The invention discloses a telescopic support leg device of engineering machinery, which comprises a fixed leg and a movable leg, wherein the movable leg is connected with the fixed leg through a horizontal unfolding cylinder, the tail end of the movable leg (11) is provided with a support cylinder (3), a telescopic rod of the unfolding cylinder (2) is provided with a fluid passage, a rodless cavity of the support cylinder (3) is communicated with an external fluid pipeline of the fixed leg through a rodless cavity of the unfolding cylinder (2) and thea fluid passage (211), in addition, an elastic element extending and retracting in the vertical direction is arranged in the support cylinder (3), one end of the elastic element is connected with the top wall or the bottom wall of the support cylinder (3), and the other end of the elastic element is connected with a support rod (32) of the support cylinder (3). The telescopic support leg device has the advantages that the arrangement of work pipelines of the support cylinder is very simple, the installation and the maintenance are more convenient, in addition, when the arrangement mode is adopted, the friction damage between a support leg and the work pipeline of the support cylinderleg when the support leg extends and retracts is avoided, and the work reliability of the support cylinder is enhanced. In addition, the invention also discloses the engineering machinery comprising the telescopic support leg device.