The invention provides a log write-in method and a server side. The log write-in method is applied to the server side and is characterized in that the server side provides a plurality of service threads and each service thread is used for outputting a log request. The log write-in method comprises the following steps: S1, providing an input interface used for intercepting whether any log request output by the service threads is available, and performing the step S1 continuously if the answer is negative; S2, correspondingly receiving a log output by a certain service thread according to the log request and storing the log in a cache region with the priority corresponding to that of the corresponding service thread according to the priority of the service thread; S3, providing an output interface used for writing the log in the cache region into a disk when the read-write frequency of the disk at the service side is lower than a preset threshold value. According to the technical scheme, the log write-in method and the service side have the benefits as follows: the log write-in efficiency is higher, the work performance of the server side is further improved, and the defect that the work performance of a server is reduced due to high write-in frequency of logs in the prior art is overcome.