 The purpose of this study is to explore and assess possible outcome benefits of lactate clearance30 vs ScvO2 70 in 6 hours as the protocol goal that evaluated adequacy of during early resuscitation of septic shock through a single-center randomized controlled study. The investigators anticipate to collect 300-400 qualified patients with septic shock who were selected from critically ill patients admitted to the Department of Critical Care Medicine. The participants can be randomized divided into lactate clearance group and SCVO2 group. The investigators compared the treatment and the relevant parameters changed after different target. 28-day mortality, ICU and hospital lengths of stay, ventilator-free days, and new emerged organ failure were collected and compared. 28-day survival curves were drew between these two group. And the adverse events of the treatment have also been compared. Through this study, the investigators want to answer that whether lactate clearance-oriented therapy can reduce the mortality in patients with septic shock, compared with ScvO2-oriented protocolised therapy. 