I have got Chinese Z-Visa. Is it essential for me to buy a round trip ticket or is a one-way ticket OK? I am planning to travel using Thai Airways and I will fly from Lahore, Pakistan holding a Pakistani passport.
With a Z visa you do not require a return ticket. That being said, it is possible that Thai Airways will not be aware of this, and will expect a return ticket to board the flight. Your best bet would be to contact Thai Air and verify their policy on this.