The study of micro flame is very important for the design of an efficient, safe micro-burner. An experimental study of small jet diffusion flame was performed. Combustion tests under strong electric field were carried out in ceramic tube burners with the inner diameter of 1.0mm using liquid ethanol as fuel. The relationship between flame dimension and Reynolds number with the voltage was analyzed experimentally. The experiments were conducted with the voltage ranging from 0V to 10000V, and with different electrode spacing (3cm, 5cm, 7cm). The experimental results show that under electric field, the Reynolds number of ethanol vapor increases with increasing the voltage. And the Reynolds number may become instable when the electrode spacing is too large. A strong electric field can reduce soot emission from the flame.