This paper conducts the numerical design of the outlet guide vanes (OGV) and nozzle for a Co-flow Jet (CFJ) micro-compressor actuator to maximize the efficiency. For CFJ active flow control, the embedded micro-compressor actuator is required to produce the static pressure ratio (πs−t ) lower than 1 to match the low pressure of CFJ airfoil leading edge suction peak. Therefore, a high efficiency outlet guide vane with a nozzle designed to deswirl the flow and decrease the outlet static pressure. Parametric studies of the OGV deswirl angle and flow path geometrical parameters are studied including: the flow path diverging location and diverging angle for the OGV, the flow path converging location and converging angle for the nozzle. The numerical results show that for the OGV, a flow path with a 7◦ front diverging (33%) is beneficial to decrease the OGV outlet Mach number. For the nozzle downstream of the OGV, a 10◦ rear converging location at 80% streamwise length is able to achieve the targeted static pressure ratio of 0.987 with a minimum loss. It is also found that deswirling by the vanes with a converging nozzle helps to reduce the vane loading and loss. The final optimized compressor has outlet swirl angle of 5.45◦, total pressure recovery of 98.7% and compressor efficiency of 75.05%. The efficiency analysis of a low pressure ratio compressor is conducted. In addition to the stage efficiency and total pressure recovery of OGV and nozzle, it is found that a higher stage total pressure ratio is beneficial to achieve a higher full compressor efficiency. The full compressor efficiency is sensitive to the total pressure recovery of the OGV and outlet duct. For the present design with the stage pressure ratio of 1.13, if the total pressure recovery drops from 0.99 to 0.98 by one point, it costs the full compressor efficiency loss by 8 points from 77% to 69%. It is hence crucial to have an efficient design of the OGV and outlet duct. The penalty is decreased if the stage total pressure ratio is increased.