In this work, the ballistic transport characteristics of carbon nanotube field effect transistors (CNTFETs) and its dependence on channel length are investigated based on the fabricated high performance CNTFETs with interface engineering. By utilizing a self-established CNTFET virtual source (VS) model, the mobility, injection velocity, and ballistic efficiency of 200 nm and 50 nm CNTFETs were extracted. Comparing CNTFETs with Si and GaN HEMT devices at similar dimensions, CNTFETs exhibit superior mobility and ballisticity. The VS device compact model was incorporated with the SPICE model, and the constructed CNTFET inverter and ring oscillator circuits show a 26.2% increase in the high/low level conversion rates and a 1.68 times frequency improvement , respectively, as compared with the FDSOI circuits at the same node.