The utility model provides a little differential pressure sensor of magnetic fluid for manned passenger cabin of aircraft, is applicable to the poor measurement of minute -pressure. The device includes: clear glass pipe (1), a magnetic fluid encircles (2 -1), and the 2nd magnetic fluid encircles (2 -2), an induction coil (3 -1), the 2nd induction coil (3 -2), a cylindrical permanent magnet (4 -1), the 2nd cylindrical permanent magnet (4 -2), iron core (5). A cylindrical permanent magnet (4 -1), the 2nd cylindrical permanent magnet (4 -2), iron core (5) be common to constitute compound magnetic core, clear glass pipe (1) open end and the manned passenger cabin UNICOM of aircraft, and the initial pressure of blind end be atmosphere pressure P0, and the pressure difference at compound magnetic core both ends makes compound magnetic core move clear glass pipe (1) in, until both ends pressure balance, through to the judging of output voltage, can understand the interior pressure change of the manned passenger cabin of aircraft in real time to adjust the pressure in the manned passenger cabin of aircraft in real time through the PID system, guarantee safety.