The invention discloses organosilicone boric acid ester modified ammonium polyphosphate and a preparing method and application of the organosilicone boric acid ester modified ammonium polyphosphate. The preparing method of the organosilicone boric acid ester modified ammonium polyphosphate can solve the problems that a carpet is prone to absorbing moisture and getting damp and is simple in function and the flame resistance is reduced after flame-proof treatment through ammonium polyphosphate. The preparing method comprises the steps of synthesizing boric acid ester modified amino siloxane to obtain organosilicone boric acid ester, and using the organosilicone boric acid ester to modify the surface of the ammonium polyphosphate. After the modified ammonium polyphosphate is applied to flame-proof resistance of the carpet, the carpet is dry in touch compared with a carpet treated by unmodified ammonium polyphosphate, and the flame resistance is improved. In addition, the antistatic performance, the antibacterial performance and the wearing resistance are achieved.