Thank you all for your advice and help!
So there is no such a way to make a conditional way points in the FMC. If the SID is like that i can use the HDG sel first until I got the next leg in the flight. Then use LNAV.
Thanks again, and I like the professional here. Though English is not my native language， I can still got a lot of help here. But sometimes maybe it will get you some trouble to understand what I'm saying!
