Two of China’s biggest Internet firms are coming together after online video giant Youku Tudou announced a partnership with microblogging firm Sina Weibo.

The deal sees Sina gain access to Youku Tudou’s video library (of 4,500 movie titles and 2,700 TV series) as it aims to beef up its multimedia content approach in the face of recent deals from rivals, which included Chinese search leader Baidu’s acquisition of PPS Video for $370 million

In exchange, Sina will help promote the video giant and its content to its 500 million plus registered users through strategies for both its desktop and mobile platforms. Youku Tudou — which formed from a billion dollar merger between YouKu and Tudou last year — is reportedly China’s most trafficked video site, and claims 170 million daily views from mobile devices alone.

The tie-in will see Sina serve users a ‘personalized recommendation section’ inbetween Weibo posts (similar to tweets). Search results for TV-related content will bring up thumbnails that link through to a page that provides links to the Youku and Tudou videos sites, as well as featured reviews, mentions of the content from other Weibo users and additional information.

The duo will also “cross-promote” each others most popular, ‘premium’ members and their content. So that’s likely to mean celebrity Weibo posts, or Youku Tudou content being shown on the other service in an effort to help drive traffic to both services.

The partnership will kick off next month, the companies said in an announcement made today.

Sina has change the way many Chinese citizens and China watchers interact online, allowing them to enjoy greater freedom (but not freedom itself) online and gain easier access to news and opinions, but it is under pressure from Tencent-owned messaging service WeChat.

Chairman Charles Chao previously acknowledged that WeChat is seeing users spend less time on the Sina Weibo service, and the move to work with Youku Tudou is one that the company will hope provides more traffic and a more engaging experience.

Youku Tudou already accounts for nearly half of all Weibo retweets that contain video links — according to a Deutsche Bank report — and a closer alliance is likely to increase its traffic and visibility among many of China’s Internet users. Given Baidu’s acquisition of PPS Video and its existing iQiyi video unit, the Weibo alliance could prove to be a key one.

Data from Analysys — covering all devices — gives Youku Tudou a 30.2 percent share of China’s online video market, followed by Sohu 10.3 percent, iQiyi on 9.7 percent and PPS on 7.1 percent.

Sina is worth $3.25 billion based on a recent $586 million investment from e-commerce giant Alibaba Group.

Aside from its hugely popular Weibo service, the company also runs Internet news portals, which include the high profile Sina Tech news site.

Headline image via Spencer Platt / Getty Images