[en] Highlights: • A new launcher mirror unit was developed based on adjusting the water cooling line layout and designing the detachable mirror. • In situ replacement the reflector of the launcher mirror inside the device could be realized with the new design. • The new launcher mirror employs a type of dot-matrix water cooling channel structure. • Temperature distribution and thermal-stress of the new mirror were analyzed by fluid-thermal-solid coupling analysis. Significant progress has been achieved on EAST tokamak with the electron cyclotron resonance heating (ECRH), but the maintenance current EC launcher is very complicated after each campaign period. In order to reduce the maintenance frequency and cut down the maintenance cost, a new launcher mirror unit was developed based on adjusting the water cooling pipe lines layout and designing the detachable mirror. It improves the bending conditions and extends the life of the metal hoses effectively. Meanwhile, in situ replacement of the mirror reflector inside the device could be realized with the new design. The new launcher mirror employs a type of dot-matrix water cooling channel structure. It is demonstrated that the cooling design satisfies ECRH operating requirement with lower mass flow by fluid-thermal-solid coupling analysis.