The　ground　of　Chengdu　Metro　Line　No　1　alignment　is　typical　cobble　stratum　and　the　cobble　geometrical　properties　are　analyzed　statistically　through　on-the-site　screening　experiments　and　digital　image　technique　method.　Its　average　value　of　the　diameter　of　the　cobble　of　the　Mtro　Line　No.1　alignment　is　38.23　mm　and　the　average　value　of　the　length　ratio　between　the　longest　axis　and　the　shortest　axis　is　1.54.　The　average　angle　between　the　cobble　long　axis　and　horizontal　direction　is　32.72°.　The　cobble　geometrical　shape　is　assumed　to　be　an　ellipse.　Based　on　the　numerical　modeling,　the　influence　of　cobble　geometrical　properties　on　the　equivalent　elastic　modulus　of　cobble　stratum　was　studied.　The　numerical　results　show　that　the　equivalent　elastic　modulus　increases　with　increasing　of　cobble　percentage　content.　The　equivalent　elastic　modulus　increases　with　increasing　of　the　angle　between　the　cobble　longest　axis　and　horizontal　direction.　While　the　equivalent　elastic　modulus　decreases　with　increasing　of　the　length　ratio　between　the　longest　axis　and　the　shortest　axis　of　cobble.　On　the　basis　of　uniform　strain　assumption,　analytic　solutions　are　derived　from　the　theoretical　approach　for　equivalent　elastic　modulus.　The　analytic　solutions　were　validated　by　the　numerical　modelling　method.　The　results　indicate　that　the　equivalent　elastic　modulus　derived　from　the　theoretical　and　numerical　model　is　closely　matched.　The　analytic　solutions　are　helpful　for　improving　the　understanding　of　deformation　for　such　ground　condition.