The invention discloses a data writing and reading method in a cache as well as a cache controller. The method provided by the invention comprises the steps of receiving data writing request and to-be-written data in data transmitted by a processor, wherein the data writing request contains the address of a high-speed cache block; reading first data used for caching the high-speed cache block of the to-be-cached data in the high-speed cache block; using written data to replace partial or full data in the first data according to the address of the high-speed cache block, so as to obtain second data; detecting whether the second data is zero; if the second data is zero, setting the zero data identifier bit of the high-speed cache block used for caching the to-be-written data to be true, so as to finish data writing. Therefore, the power consumption and consumed time caused by the writing of the second data can be effectively prevented.