The former Asian number one recovered from a bogey on the 11th - his second - with an impressive nine birdies to move two shots clear of Australian Anthony Brown.
Joint first round leader Brown returned to the clubhouse with a 69 while Japan's Shingo Katayama (65) is a stroke further back in a share of third with Michael Hendry (67) from New Zealand.
"My form has been good this year and when my putter works like today then it all comes together," said Liang, who shot 70 in the first round. "I was a little tired yesterday and could not concentrate. I felt much better today.
"There was less wind this morning which helped but it was really hot and humid. The key today was also to stay patient."