An objective of the present disclosure is to provide a method and apparatus for accessing time series data. The method according to the present disclosure comprises: acquiring time series query information; determining corresponding time offset information based on the time series query information, the time offset information including hour information, minute information, and offset information; finding a leaf node in a time tree corresponding to the time offset information based on the time offset information; and querying in the leaf node based on the offset information, to acquire corresponding time series data. Advantages of the present disclosure lie in possessing a lower complexity and improving query efficiency of the time series data. In addition, the memory is less occupied, and out-of-order writing is supported.