This paper presents basic characteristics of flow control with a nano-second pulse plasma actuator in low Reynolds number flow. Schlieren visualization in quiescent air verifies that nano-second pulse (NSDBD) actuation can generate compression waves and near-wall flow, whereas burst wave (ACDBD) actuation generates only near-wall flow. The results indicate that strength of a compression wave is independent of pulse repetition frequency. Strength of a compression wave gets stronger with increasing pulse peak voltage because rate of voltage dV0p/dt increase and localized heating is strengthened. Nano-second pulse actuation is applied to leading edge separation control of Re = 63, 000 (free stream flow velocity 10m/s). To understand flow-control characteristics of nano-second pulse actuation, two types of discharge, NSDBD and ACDBD, two types of actuator position, x/c = 0.05 and 0.1, and two types of actuator direction, co-flow blowing and counter-flow blowing, are examined. Generally, flow-control characteristics of NSDBD actuation is very similar to that of ACDBD actuation. With the same voltage amplitude, NSDBD actuation has better control capability than ACDBD actuation. Note that consumption power of NSDBD is 10 to 1000 times larger than that of ACDBD. With an actuator at more downstream position (x/c = 0.1), control capability significantly decreases and separation cannot be suppressed at all. Also results show that NSDBD actuations in counter-flow blowing are worse than those in co-flow blowing for separation suppressing. This indicates that near-wall flow of small momentum from nano-second pulse discharge affects flow-control capability in this Reynolds number condition.