应是who is he。who is he是主系表结构，he在这作主语，him是he的宾格，只能作宾语。主格放在句首做主语和表语，宾格放在句末或句中做动词和介词的宾语。
双语例句
1、'Who is it?' he called. — 'It's your neighbor。'
“是谁啊？”他问道。——“是你的邻居。”
2、I wonder who he is, where he came from and why he came.
我很想知道他是谁，从哪里来，来干什么。
3、Who is he? From where has he come from?
他是谁？从哪里来？
4、Who is he going to show some pictures to?
他要把一些照片给谁看？