Deploying Wireless Sensor Networks (WSN) securely still requires users to have certain skills and exert effort. In the near "sensor everywhere" future, a much simpler method for deploying WSN will be necessary for end-users. We propose LiDSN(Light Communication for Deploying Secure Wireless Sensor Networks) which enables users to achieve deployment tasks via simple interaction. LiDSN leverages light-based communication between an LED and a light sensor in order to add a new sensor node securely into existing WSN. Through touching interaction, a new sensor node ID and secret key can be transmitted to the WSN, and then the WSN is able to identify which node should be added while maintaining the security of the WSN.