The cost estimation of the product life cycle was researched. On the one side, the life cycle cost present value for manufacturer was estimated, including mainly of target cost, service cost and fault compensation. And a life cycle cost estimation model for manufacturer, which combines target cost and proportion cost estimated, was proposed. On the other side, the life cycle cost present value for user was estimated, including mainly of purchase, installation, commissioning costs in beginning and labor, maintenance, depreciation, maintenance costs in operations. And another life cycle cost estimation model for user, which combines process cost and proportion cost estimated, was proposed.