Hi, I installed Quartus Prime 18.0 Lite Edition on UBUNTU 16.04 LTS , and it is OK. But , when I start RTL simulation tool It can not lunch MODELSIM

Have you downloaded and installed the ModelSim tool. Each of the tools have separate installers. If you have installed only the QuartsLite tool using the "Quartuslite18.0.xxx.run" file, this will install only the Quartus tools and not ModelSim. To install ModelSim, download and install the ModelSim Intel FPGA starter pack from the following link:

http://download.altera.com/akdlm/software/acdsinst/18.0std/614/ib_installers/ModelSimSetup-18.0.0.614-linux.run

Once the download completes, change directory to the download location and execute the following commands

sudo chmod 775 ModelSimSetup-18.0.0.614-linux.run
 
./ModelSimSetup-18.0.0.614-linux.run

This will launch the modelsim setup. Follow the onscreen instructions to install it. Once installed, you should be able to launch it via Quartus or terminal prompt using ./vsim command.