Carbon tubule nanocoils produced by the catalytic thermal decomposition of acetylene have good electric conductivity and excellent mechanical strength, which enable them to be applied to electronic devices. We have fabricated field emitters using carbon nanocoils with different diameters and lengths. The field emission measurement shows that the turn-on voltages of carbon nanocoil field emitters are dependent on the diameters of the coiled tubules. Decreasing the thickness of iron film and the flow rate of acetylene gas can decrease the average diameter of grown carbon nanocoils. Decreasing the growth time can obviously decrease the average length of the coils. It is expected to use carbon nanocoils with small diameter and short length to fabricate high performance flat panel display, which is driven at low voltage and has high resolution and brightness.