Abstarct: Connection and utilizing close islands to the coast areas and its resources and structuralization proper paths between the islands and coasts, usually is done by maritime transport, arivation, bridge or tunnel that in the most of southern islands, maritime transportation is concerned currently. According to sea depth, long distance between the coasts, creating an obstacle to navigation, environmental issues and bridges strategic consideration, connecting sub-sea tunnel between Kharg island and the main coast has been studied. Aghajari formation has extend exposure on Khark island and consist of red marls, fine brown sandstones and gray marl laxyers. with using of data from implemented projects in the tunnel zone, geotechnical and geological characteristics of optional tunnel paths assigned and material and thickness of geological units in the tunnel area include: laxyers of sands and marine sediments with 8.5 meters constant thickness, calcareous sand stone with 7.5 meters constant thickness and marl with thin alternating laxyers of silt and fine sand. According to maximum of transportation wagons` dimensions and other standards, tunnel diameter is considered 8 meters, and according to bedrock depth surface section affections on tunnel design, tunnel rock cover in the whole of the path is 30 meters and with this rock cover and standard inclination, depth and length of tunnel in all of the 4 paths is considered. With stability analysis of Khark island connection tunnel to main coast with finite element software, Plaxis, and methods of the critical shear stain, the tunnel sections are stable. Parametric sensitivity analysis of various parameters is conducted for tunnel stability. According to tunnel length and geological conditions, utilizing traditional methods for drilling is canceled and tunneling will done with closed-Shield machine and baxsed on the soil particle size distribution curve, EPB is chosen as the main machine for tunneling. Using empirical methods Trzaqy to estimate face perresure that pressure levels between 460 to 480 kPa has been determined. According to the experience of performed projects, the minimum cost of excavation and tunnel construction (The shortest path), 153 million Euros and 4.5 years is estimated. Sensitivity analysis and parametric studies due to uncertainties in the parameters used to determine the importance of each them. baxsed on the parametric studies, with increasing the marl laxyer cohesion and angle of internal friction, the maximum movement of the tunnel with the maintenance constant and the tunnel without the maintenance reduced, with increasing marl laxyer Modulus, the maximum movement of the tunnel reduced also by increasing the ratio between the tension the maximum movement has increased in tunnel. baxsed on the sensitivity analysis of the tunnel geometric parameters, with increasing the depth and diameter of the tunnel, the tunnel maximum movement increased.