How long does it take to explore the central line of Mt. Laoshan? Can it be done in half a day?

It is hard for you to do it in half a day. I travel there using one day and I did not not cover all the places along the central line.

Mt Lao is a huge area, you could spend a week, or more exploring it. many of the areas require you being in very good physical condition as the climb from the ocean to the Buddhist shrine on the ocean side requires climbing about 5000 stair steps. As far as I know, there are no "quickies" at Mt Lao, the bus rides are time consuming and the climbs are time consuming. If you only have half a day, do the Tsing Tao Brewery Tour and the Oympic Sailing Center/ May 4th Square.