用个Span简单多啦

[misakuo]

    SpannableString spannableString = new SpannableString("头部文字 10/30 底部文字");
    spannableString.setSpan(new RelativeSizeSpan(1.4f), 5, 10, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    spannableString.setSpan(new ForegroundColorSpan(Color.RED), 5, 10, Spanned.SPAN_INCLUSIVE_INCLUSIVE);
    textView.setText(spannableString);