The invention provides a garden weeding agent. The garden weeding agent adopts a formula containing the following raw materials of 10 to 13 parts of herba ageratum conyzoides, 5 to 8 parts of ambrosia artemisiifolia, 2 to 4 parts of dodecyl dimethyl benzyl ammonium chloride, 3 to 5 parts of clopyralid, 5 to 7 parts of folium monochoria vaginalis, 4 to 8 parts of semen cuscutae, 7 to 13 parts of soybean extracting solution, 2 to 4 parts of tea polyphenol, 2 to 7 parts of garlic, and 40 to 63 parts of water. A method comprises the following steps of drying the herba agerati conyzoides, the ambrosia artemisiifolia, the folium monochoria vaginalis and the semen cuscutae, and adding into a crushing machine to crush; adding the dodecyl dimethyl benzyl ammonium chloride, the clopyralid and the crushed material into a stirring machine, adjusting the temperature to 20 to 23 DEG C, and uniformly mixing; adding the left component into the mixture, treating for 5 to 10min by ultrasonic waves, separating solid and liquid, and collecting filtrate; heating and concentrating the filtrate, so as to obtain the garden weeding agent. The garden weeding agent has the advantages that by adding the semen cuscutae, after the weeding agent is sprayed, the moistening time can be prolonged, and the action time of medicine effect is prolonged; by adding the soybean extracting solution and the garlic, the functions of diminishing inflammation and sterilizing are realized.