The invention discloses an SSD-based (Solid State Disk) cache management method and system. The SSD-based cache management method comprises the following steps: step 1, sending a read-write request, checking whether a cached DRAM (Dynamic Random Access Memory) hits data, searching a hash list, judging whether the data is existent, reading the data from the cached DRAM and returning the request if the data is existent, and reading data to the cached DRAM from a HDD (Hard Disk Drive) and carrying out step 2 if the data is nonexistent in the cached DRAM; step 2, carrying out data screening by using a two-level LRU (least recently used) linked list and a Ghost buffer, and identifying data heat; and step 3, carrying out self-adaptive change calculation on the length of the two-level LRU linked list, acquiring the granularity of a page cluster when the second-level LRU linked list of the cached DRAM is full, taking C pages behind the second-level LRU end as a whole body to replace the cached DRAM, and writing the C pages into an SSD in a large granularity, wherein the page cluster size is C pages, and C is an integral multiple of Block page number in the SSD.