The invention discloses an OTP memory, data writing and reading methods thereof and a security chip. The data writing method of the OTP memory includes the following steps: S1, carrying out block dividing on the OTP memory in physical space to form n+1 blocks of storage areas, wherein n is a positive integer which is greater than 1, and the n+1 blocks of storage areas include n blocks of data storage areas and one block of address storage area which is always in a readable state; S2, generating a random sequence through a random-number generator, randomly selecting one block from the n blocksof data storage areas according to the random sequence, and defining the same as an address recording area; S3, sequentially writing first addresses of n-1 blocks of data storage areas into the address recording area according to a random order, and writing to-be-stored data in each block of data storage area according to a successive order of writing; and S4, writing a first address of the address recording area into the address storage area which is always in the readable state. According to the data writing method and reading method of the invention, difficulty of acquiring the data, whichare stored in the memory, by a cracker can be increased, and storage security can be improved.