In ~/.atom/styles.less, add the below css setting

## Windows
```
atom-text-editor {
  font-family: "Microsoft JhengHei", sans-serif;
  //font-size: 14px;
}
atom-pane {
  font-family: "Microsoft JhengHei", sans-serif;
}
```

## Linux

If you are using Ubuntu, you have to install ttf-wqy-microhei and fonts-wqy-microhei
```
atom-text-editor {
  font-family: "WenQuanYi Micro Hei Mono", sans-serif;
  font-size: 14px;
}
atom-pane {
  font-family: "WenQuanYi Micro Hei Mono", sans-serif;
}
/* Make markdown preview to display chinese */
.markdown-preview {
  font-family: "WenQuanYi Micro Hei Mono";
}
```