China - which already owns over half of Tajikistan's public debt - has long sought to increase ties in the ex- Soviet Central Asia region which Moscow has traditionally viewed as its backyard.
Construction of the mammoth parliament project is expected to begin later this year and the money has been "allocated by the Chinese side," Tajik official Jamshed Akhmadzoda said.
China is a vital source of investments in mainly agrarian Tajikistan, which is also strongly dependent on remittances sent home by migrant workers in Russia.
Strategically located on the border of China's restive Xinjiang province and conflict-wracked Afghanistan, Tajikistan is the poorest of the former ex-Soviet republics.
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That has however not stopped authorities under strongman ruler Emomali Rakhmon from splashing out on a string of lavish projects, including a super-sized library and what was once the world's tallest flagpole.
For the most part, Chinese economic assistance to Tajikistan has targeted key infrastructure projects including roads and railways linking the republic's north and south.
Tajikistan is a key route for drug smugglers trafficking heroin from Afghanistan to Russia and Europe.