The glide test was conducted on April 29.
Other tests and check-ups are under way, according to the China Aviation Industry General Aircraft Co Ltd.
Designed to be the world's largest amphibious aircraft, the 37-meter AG600 with a wingspan of 38.8 meters, has a maximum take-off weight of 53.5 tonnes.
It can collect 12 tonnes of water in 20 seconds, and transport up to 370 tonnes of water on a single tank of fuel, state-run Xinhua news agency reported.
Aviation Industry Corp, Chinese state-owned aerospace and defense company said in March that AG600 would embark on its maiden flight over land in late May and on water in the second half of 2017.
The aircraft developer has received orders for 17 AG600s.