As I am not a native speaker, so when I speak english, I have to think in my mother language and then translate into english, it makes me like a stammerer , I was wondering if it is possible to think in english directly for non-native english speaker to increase the fluency of english speaking. Please advise.
Immersion helps - I think it's probably essential. A good start is to wean yourself off dictionaries that just give translations. (Even if you knew such a dictionary word-for-word [impossible] it would at best make you a very hesitant speaker.)