The present invention discloses a reversing value (1000) which includes a pilot valve (1200) and a main valve (1100). The main valve (1100) includes: a valve body (10) with a valve chamber (20), wherein the valve chamber (20) is provided with a valve seat (30) therein, and the valve seat (30) is provided with a plurality of valve ports (40) thereon; a plurality of flow path ports (50) are correspondingly communicated with the plurality of valve ports (40); a sliding valve core (60) matching the valve seat (30). The plurality of valve ports (40) include a first valve port (41), a second valve port (42), a third valve port (43), a fourth valve port (44), and a fifth valve port (45). The plurality of flow path ports (50) include an S port (S), an E port (E), a C port (C), a D1 port (D1), and a D2 port (D2). When the sliding valve core (60) slides to a first preset position, the D1 port (D1) is communicated with the E port (E), and the S port (S) is communicated with the C port (C). When the sliding valve core (60) slides to a second preset position, the D2 port (D2) is communicated with the C port (C), and the S port (S) is communicated with the E port (E). The present invention also discloses a cooling system with the reversing valve (1000). The reversing valve (1000) can effectively solve the problem in the prior art that the pressure of high pressure fluid in a valve chamber of a reversing valve is unstable in the switching process.