The invention discloses a secure non-adjacent form realization method in a chip. According to the method provided by the invention, when carrying out NAF calculation to data K on a smart card or a non-smart card, on hardware or software, through inserting moderate pseudo-operations in the operation process, an attacker cannot effectively identify the influences of operation data on power consumption from the power consumption; therefore, side-channel attacks are resisted; moreover, the opportunities of inserting the pseudo-operations are disordered through random numbers; the attacker cannot accurately judge and analyze default injection points; and therefore, the default injection attacks are resisted. In adoption of the method provided by the invention, the side-channel attacks and the default injection attacks can be resisted; the security of the chip can be improved; the method of the invention is applicable to the security algorithm realized by the hardware and software in the chip, is especially applicable to financial cards and transportation cards applying password security chips.