Straight rebar connector widely used in many domestic projects, has dominated the domestic market reinforced mechanical connection. According to statistics, the annual number of connections for a variety of joint projects straight thread has reached hundreds of millions, if pressed sleeve connections with taper thread and reinforced joints compared to annual savings for the state for at least several thousand tons of steel, both in human, material and financial resources or energy conservation, environmental protection, both for the country to create a considerable economic and social benefits. Straight threaded joint strength is relatively high, the use of reinforced steel to cold hardening process it, the strength of the threaded joint straight greatly improved. Straight threaded joint performance is relatively stable, the connection process is relatively simple, does not require the use of artificial control connections. In the application range of the basic limitation is not too much, but the operation is not used in some occasions. Straight nipple does not occur when using a mismatch, it is relatively easy to test, operation is relatively simple, ordinary learning very fast.