The two countries have drawn closer in recent years, including since the outbreak of the Ukraine war in 2022, AFP reported.
Xi's trip to Russia last week drew fire from Kiev's allies.
Beijing says it is a neutral party to the conflict and has made indefatigable efforts for peace.
On Thursday, in response to a question linked to Xi's visit asking how China would promote military-to-military ties with Russia, the defense ministry said the relationship was "operating at a high level".
"The Chinese military stands ready to work with the Russian side to further deepen strategic mutual trust, step up strategic communication, and expand practical cooperation," defense ministry spokesman Jiang Bin said in a response posted to social media platform WeChat.
The moves would "enrich the content of China-Russia comprehensive strategic partnership of coordination for a new era", Jiang said.
He added that they would also "contribute to maintaining and strengthening global strategic stability".
After a lengthy meeting with President Vladimir Putin on his trip, Xi said China's ties with Russia brought "positive energy" to a turbulent world.
He added that both nations stood firm against "hegemonic bullying" -- an apparent swipe at the United States.
Putin, for his part, told reporters he and Xi had held "traditionally warm, friendly" talks and addressed the Chinese leader as his "dear friend".