The invention of the excavator boom claim relates to a hydraulic control device for controlling the turning complex operation, particularly distinguish the boom control spool to the boom first speed control spool (11A) and a boom second speed control spool (11B), each second hydraulic pump (P2) and the first hydraulic pump (P1) side and connected in parallel lines (20,17) in the by-pass line (15), turning the control spool (13) has a first hydraulic pump boom than the second speed control spool (11B) (P1) on the upstream side through the parallel lines 16 connected in parallel to the first hydraulic pump (P1) the boom second speed control spool (11B) along with the, and the boom 1 in the control spool (11A) and a boom second speed control hapyu line 25 connecting the outlet port of the spool (11B) includes a variable T celebrate hapyu line in accordance with the boom control signal pressure outputted from the pilot control valve 24 is installed and a turn first valve (30), the turning first valve 30 is proportional to the aperture-adjustment bridge celebrate area depending on the boom control signal pressure intensity acting on the pressure receiving portion is then at the rear end of the variable T football between (X) and the variable T football cross (X) It is provided with a bleed-off section (Y) to maintain a constant opening area. Excavators, Boom swing composite operation, first swing valve, variable throttle, bleed-off, sloping operations phase difference