Objective　To observe the anesthetic effect of ultrasound guided lateral approach and modified medial approach costoclavicular space (CCS) brachial plexus block. To evaluate the clinical value of CCS via modified medial approach and to explore a new approach for brachial plexus block.　Methods　Sixty cases scheduled for forearm and hand surgeries were divided into the lateral approach CCS group (group C) and the modified medial approach CCS group (group M) by random number table, 30 cases in each group. Both groups were treated with 0.5% ropivacaine 20 ml for CCS brachial plexus block. The performance block time, the onset of block time and the duration of block time were recorded. The degrees of sensory and motor blockade were assessed at 30 min after anesthetic injection. Also, the adverse reactions were observed.　Results　The anesthesia performance block time of group M was shorter than that of group C (P<0.05). The onset and maintenance time of anesthesia and the degree of sensory and motor blockade after the injection 30 min in two groups were similar (P>0.05). There was no adverse reaction in both groups.　Conclusions　The modified medial approach CCS can be safely used for brachial plexus block, which is easier to operate.