Australian thermal coal continues to face delays at Chinese ports, with the slowdown a key topic of discussion when Senator Birmingham met his counterpart in Beijing on Saturday.
The Australian trade minister said he had been reassured the issue was not a discriminatory practice.
Chinese authorities have blamed environmental checks across different products for the delay.
"I've asked them to try to work with our authorities so that Australian businesses can better understand what those checks are and how they're being applied so that we can ensure efficiency there," Senator Birmingham told Sky News on Sunday.
He said there may be other factors influencing the slowdown, including China aiming to help its domestic coal producers by putting tighter controls on imports.
"There may be some broader issues at play when it comes to China seeking to manage the volumes of thermal coal coming into the country," Senator Birmingham said.
He said Australia wanted to get to the bottom of whether environmental checks or supply management was the root of the issue.
But the relationship between Australia and its major trading partner remains strong, the minister said.
"Overall you're talking about a relationship that has seen phenomenal growth year on year for a sustained period of time," Senator Birmingham said.
"To dwell simply on a singular negative, that there are some delays of some shipments, is really to overlook the fact that economically the relationship is very sound."
It comes as China's top diplomat Wang Yi said progress on mending strained bilateral ties was "unsatisfactory" after meeting with Foreign Minister Marise Payne.
Senator Birmingham has been at the eighth Regional Comprehensive Economic Partnership ministerial meeting in Beijing.
On the sidelines of the meeting he met with Chinese counterpart Zhong Shan, but it wasn't a long-running formal sit-down.
Senator Birmingham said the 16-nation Regional Comprehensive Economic Partnership trade agreement wouldn't include work rights to Australia or the country's Pharmaceutical Benefit Scheme.
