i asked can i go to Jinan city from Beijing airport by bus

From the airport, there is no direct shuttle bus to Jinan, so you need to transfer.

If you want to take a bus, you need to go to the Liuliqiao or Zhaogongkou Long-distance Bus Station to take the bus.
To reach Liuliqiao Bus Station from the airport, you can take the airport shuttle bus line 4 to its terminal at Gongzhufen Station and change a taxi to Liuliqiao Bus Station.
To Zhaogongkou Bus Station, you can take the shuttle bus line 1 to its terminal at Fangzhuang Station. Then take a taxi to Zhaogongkou Bus Station.

In my opinion, you can take a bullet train from BJ to Jinan. From BJ airport, you can take the shuttle bus line 10 to the south railway station. There you can easily find a bullet train for Jinan easily. It is fast and the transfer is convenient.