在校期间成绩优秀可以用 "excellent academic performance during school years" 来表示。

来源："excellent" 是形容词，意为 "优秀的"；"academic" 是形容词，意为 "学术的"；"performance" 是名词，意为 "表现"；"during" 是介词，意为 "在...期间"；"school years" 是名词短语，意为 "学校年"。

例句：

He had excellent academic performance during his school years. 他在校期间成绩优秀。
She was known for her excellent academic performance during her high school years. 她因在高中期间成绩优秀而闻名。
He received many awards for his excellent academic performance during his college years. 他因在大学期间成绩优秀而获得许多奖项。