在主题的functions.php文件中添加如下代码即可：

 
add_filter('upload_mimes', 'custom_upload_mimes');

function custom_upload_mimes ( $existing_mimes=array() ) {

	// add the file extension to the array

	$existing_mimes['svg'] = 'mime/type';

        // call the modified list of extensions

	return $existing_mimes;

}

参考资料