Composite　stiffness　principle　with　biparameter　method　applied　to　reasonable　calculation　of　piles　subjected　to　laterally　concentrated　loads　on　the　top　of　piles　brought　forward　by　Wu　Heng-li,　is　extended　to　be　applied　to　retaining　structures　of　deep　foundation　pits　subjected　to　laterally　distributed　loads　(earth　pressure).　Numerical　method　of　link　finite　elements　is　brought　forward.　Then　an　engineering　example　of　the　construction　process　of　excavation　and　retaining　structures　of　a　deep　foundation　pit　with　internal　braces　is　simulated.　Reasonable　wall-soil　composite　stiffness　and　subgrade　reaction　biparameter　are　back-analyzed　by　displacement　measurements.　Compared　with　the　existing　methods,　the　results　obtained　by　this　method　are　closer　to　the　measurements.　So　it　is　shown　that　numerical　solutions　of　link　finite　elements　based　on　composite　stiffness　and　biparameter　method　can　be　more　reliable　to　calculate　retaining　structures　of　deep　foundation　pits　with　internal　braces;　and　it　has　the　reference　value　for　applications.