The invention discloses a hay mower. A 5G mobile phone which performs positioning through the big dipper is arranged on a steering wheel of the hay mower, and can remotely control the hay mower. Humanface and fingerprint recognition is set to determine the person issuing a primary instruction or determine manned driving or automatic driving. A blade is a multi-tooth hay mowing cutter, and the side edges of transverse teeth of an apical tooth (25) of the multi-tooth hay mowing cutter are arcs with equal-angle spirals; upper die forming blocks (25a) and lower die forming blocks (25b) of a steelplate punching drawing die are multiple pressing blocks at equal intervals or by equal angles; a siphon tube is arranged on the blade, multiple short soft mop cloth strips are arranged in the circumference of a chassis, and an air cushion is formed between the chassis and a lawn; a flexible comb is arranged on a bumper, a magnetic force detector and a Doppler detector are further arranged, and liquid containing growth vitamins is dropped out of the siphon tube arranged on the haw mowing blade, has the effect of mixing smashed weeds for supplementary feeding, and further has the effect of relieving wounds of cut weeds to promote growing.