In wireless sensor network consider the secure transmission scheme in distributed detection scenario. In this context consider the passive eavesdropping where Enemy Fusion Centre (EFC) located near the Ally Fusion Centre (AFC) tries to eavesdrop on wireless communication between sensors and the AFC. To ensure the confidentiality in transmission of data from the sensors, design the transmission strategy. Here consider the data confidentiality in distributed detection scenario where large set of sensors sends the local decision to the AFC over insecure wireless medium called main channel. Then AFC makes the final decision.