The combination of V-cone flow sensor and differential pressure transmitter is a kind of novel differential pressure type flow meter. It can accurately measure the fluid under variety of flow conditions in wide range of Reynolds number (8× 103 ≤ Re ≤ 5 × 107. The principle, same as that of other differential pressure type flow meter, is to measure according to Bernoulli, I. E. Energy conservation of fluids continuously flowing in closed conduits. For ideal fluids, the flow rate is proportional to square root of differential pressure.