The 23-year-old world No 82 was well superior to his vastly more experienced opponent all night, with Hendry’s struggles from his first-round win over Jimmy White continuing.
Si put together four straight half-centuries to see off Hendry, who won the first frame but then threw away a 53-point lead in the second, missing the final red, after which he never recovered.
Hendry only returned to snooker after nine years in retirement at the Gibraltar Open last month and clearly has much work to do before he can reach the World Championship proper.
He said before facing Si: “On this evidence, my game isn’t ready. I think next year I would be more realistic about my chances. I don’t think my game is ready to win four tough matches to get to the Crucible yet.
“I will try to keep expectations low, (but) the animal that I am, if I start to get form, then the expectations will rise. At the moment it is about trying to get back to playing some good snooker.”
And Si punished Hendry’s struggles to book his spot in round three as he looks to make the main tournament on April 17. He takes on Zhou Yuelong next up.
Hendry’s season is now over. Having last appeared at the Worlds in 2012, the 52-year-old will hope to improve his game for next year, when he gets another shot at playing in his favourite venue.
He admitted after losing to Si: “I had good chances to go 2-0 ahead and after that I didn’t contribute anything to the game. My game has got to improve, it doesn’t matter where the other player is ranked.
“I’ve never got any enjoyment out of losing, ever. As I said the other night I never expected to get through four matches here, not in the slightest, but I hoped that after coming through that match with Jimmy, which was very scrappy, I’d relax into a bit of form here.
“He can play, but everyone can play if you don’t put them under any pressure. I made it far too easy for him tonight.
“I have to bring my practice table cue action to the match table. I hit the ball dreadfully, and that drains your confidence.
“The pink I missed right at the end was just like one I missed against Jimmy White, and I was thinking about it. Every shot becomes a test.
“If you make it easy for anyone, it doesn’t matter where they’re ranked, they’re going to pot balls and they’re going to beat you.”
Stephen Hendry vs Xu Si final result
Best of 11 frames
RESULT: Stephen Hendry 1-6 Xu Si
Frame scores: 67-34, 64-66, 0-76, 16-88, 8-67, 9-83, 25-72