I have control of star spring and have a unit there. Can i choose to play baron nashor on star spring to trigger its move a unit in starspring effect?

No — not if Baron Pit isn't already on the board. Baron Nashor's "as you play me" text is a replacement effect: he replaces entering your chosen location with entering the Baron Pit, so he never actually enters Star Spring and Star Spring never sees a unit "played here."

Rule 369.3 gives this exact example — the entry into Baron Pit replaces the event of him entering at his original play location. So you'd play him to Star Spring, the Baron Pit token gets created, and he enters there instead; Star Spring's trigger condition is never fulfilled.

The one exception: if a Baron Pit is already on the board, there's nothing to create, so the "if you do" fails and he enters at your chosen location — Star Spring — and Star Spring's ability does trigger. Also note the ability moves another unit you control there to base, not Baron Nashor himself.