Abstract: In order to deduce the calculation formulas of critical explosive voltage and current of bridge wire components in theory, two aspects of the research have been done. First, the values of 50% explosive voltage and 50% explosive current of Ni-Cr bridge wires with plastic and glass plug were experimentally measured and the explosive properties were summarized using the method of D-optimization. Then, on the basis of the above, the bridge wire calefactive function could be derived in analysis and the critical explosive voltage and current could be calculated. At last, the calculation values were compared with experimental values. The compared results show that the calculation values agree well with the experimental ones. That means the deduced formulas to calculate critical explosive voltage and current are reasonable in reality.