It ranks around top 50 among the 200+ boarding schools and the top 200 among the 3000+ private high schools in US. It is a decent ranking. Do realize there are many good schools in US and it’s very competitive. Besides the college readiness, the ranking is also subject to the following factors:
-Academic scores
-Students diversity
-Extracurricular Activities
-Sports performance
-Art performance
-Teachers’ quality and engagement
-Culture & Safety
So the ranking generally is different between Chinese and US rankings. They stress more on different things.