The CDC 3000 series ("thirty-six hundred" or "thirty-one hundred") are a family of mainframe computers from Control Data Corporation (CDC). The first member, the CDC 3600, was a 48-bit system introduced in 1963. The same basic design led to the cut-down CDC 3400 of 1964, and then the 24-bit CDC 3300, 3200 and 3100 introduced between 1964 and 1965. The 3000 series replaced the earlier CDC 1604 and CDC 924 systems.

The line was a great success and became CDC's cash cow through the 1960s. The series significantly outsold the much faster and more expensive machines in the CDC 6000 series, but the performance of the 3000's relative to other vendors quickly eroded. The line was phased out of production in the early 1970s in favour of new members of the 6000 series, and then the CDC Cyber series, initially based on the 6600 design but spanning a wide range of performance.