To Jeita Grotto from Beirut

Anyone can tell how to go to Jeita Grotto by public transportation?

You can't.

If you really want to cut down on costs, your best bet would be to grab a service up the coastal highway to Jounieh and to get a taxi from there, or get the cable car up to Harissa and try to sweet talk a local into giving you a lift, given that many people go to Harissa before going on to Jeita.

agree with SPDL. Taxi from Jounieh won't break the bank. It will probably be easy to hitch a ride back to the main road from the grotto (that's what I did)

Went last week. Got the bus numer 6 from Dora to the directons on Byblos (1.000). Got off on the highway. Grabbed a taxi on the highway for 10.000 Lira to the caves. On the way back the last taxi driver offered ride to the highway for 30.000. We refused, offered 10k. He laughed. We started to walk away, when we crossed the parking he came hooping that 10k is ok. We got another (local) guy into the taxi. For the same route he paid 2.000.

I assume you can get the same for 5.000. Just have the money in your hand show it to them and if they start talking walk away. Next will come.