Preparation method of highly-oriented horizontally-arranged boron nitride film

The invention discloses a preparation method of a highly-oriented horizontally-arranged boron nitride film. The preparation method comprises the following steps: preparing slurry by using boron nitride powder as a raw material; coating a release film with the prepared slurry to obtain a thin film; carrying out compression treatment on the thin film; repeating the coating and compression treatment steps for multiple times to obtain a pretreated film; and carrying out hot pressing treatment on the pretreated film to obtain the high-orientation horizontally-arranged boron nitride film. According to the method, boron nitride powder with a certain sheet diameter is screened to be matched with the coating thickness, the matching ratio is that the coating thickness to the boron nitride sheet diameter is (2-4): 1, more boron nitride powder is horizontally and directionally arranged before a polymer in slurry is cured and formed, and the highly-oriented and horizontally-arranged boron nitride film is obtained through