Office chair with height-adjustable backrest

The utility model relates to the field of office supplies, in particular to a backrest height-adjustable office chair which comprises a base and a backrest, a seat plate and a pair of armrests are arranged at one end, away from the ground, of the base, a transverse rod is fixed to one end, away from the ground, of the base, and a gap is reserved between a vertical rod and the backrest; the ends, away from the ground, of the vertical rods are movably connected with connecting rods, sleeves are arranged at the two ends, close to the two vertical rods, of the connecting rods, the two vertical rods are arranged on the two sleeves in a sleeving mode respectively, inserting holes are formed in the vertical rods, the multiple inserting holes are distributed in the length direction of the vertical rods, buckles are further hinged to the sleeves, and inserting rods protrude from the sides, close to the inserting holes, of the buckles. A containing groove for the buckle to move is concavely formed in the connecting rod