how to go from Shenzhen railway station to shenzhen OCt Inn in Baoan by bus, subway then

Well, do you mean the OCT City Inn near guangshen Road of in Baoan District? If so, you can take subway Luobao Line at the railway MTR station and get off at Baoan Center Station. It will be about 1.4 km from your hotel. So you can take a taxi there very fast.
Another way is to take bus no. K548 at the railway station and get off at Chuangyetianhong Station. After that, you can go to your hotel by walking about 8 min.