Disclosed are a glyphosate and its preparing method oxidate oxidate to acquire mixed liquid of glyphosat; bifter hydration, add into glyphosate agent glyphosate preparation to change it into salt, then add surface active agent as assistant into the mixed liquid of salt and the surface active agent is one or several ones from nonion surface active agent or amphoteric surface active agent or organic silicon surface active agent, mix them to be average, acquiring the . In the course, there is no need to separate glyphosate technical grade, while preparation the with the glyphosate technical gradedirectly, which has decreased the amounts of equipment and worker, without drainage of glyphosate mother liquid, it completely makes use of glyphosate technical grade, as well as reduces waste water, benefiting for environmental protection.