Yasiel Puig threw batting practice for the Texas Rangers on Tuesday -- but not the MLB squad ... the Texas Rangers of Northeast Los Angeles Little League.

The story is pretty awesome ... the team of 8-year-olds were getting ready for their usual 5pm practice when Yasiel unexpectedly dropped by the little league fields at Elysian Park, right next to Dodger Stadium, and asked if he could hang out.

Once the team, the coaches and parents realized who he was (they recognized him instantly) ... the place went crazy and let Yasiel run the practice.

We're told Puig spent 30 minutes signing autographs for everyone -- bats, gloves, hats, shirts, etc. -- and then took the mound and pitched while the kids took turns at bat.