Mobile-first is not a strategy in China, it is the baseline

In Baidu, mobile is not a segment of the traffic to be optimised for after desktop — it is the search product. The standards reflect that: the landing-page white paper, the permissions policy and Bingtong are all mobile documents, and they carry the most specific requirements Baidu publishes anywhere.

What follows structurally

• A mobile search result must land on a mobile page. Baidu asks for either a mobile site with a declared adaptation relationship submitted to it, or a responsive PC site. Serving a desktop page to a mobile searcher is a defect, not a compromise.
• The mobile page is judged against published numbers — first screen within one second, main content over half the first screen, body text at 10pt or more with line height above 1.4.
• Handset adaptation is part of the standard, including the iPhone home indicator not covering functions.

The permissions policy — the part Western sites break routinely

Since April 2019 Baidu has controlled permission demands on mobile. It is prohibited to force a user to register, log in, download an app, or open content in an app in order to:

• read the full text, view a large image, read a forum post or watch a video;
• view comments or recommendations, make a phone call, download a resource, or use other page functions.

The exception is narrow and fair: genuinely copyrighted content — books, film, music, images — is unaffected.

This makes the standard Western growth tactic — an app-install interstitial or a registration wall over ordinary content — a search violation in China rather than a conversion trade-off.

What this means for a site entering the market

The mobile page is the product. A responsive build that satisfies the white-paper numbers, with no permission walls and no floating advertising, is the baseline before any content or link work is worth doing — because a page failing those rules has its display restricted regardless of how good it is.