It is necessary for the construction and acceptance of a lightning protection project for weakcurrent equipment rooms to have a comprehensive， practical and the applicable judgment method to decide whether the capability of a lightning protection system meets the requirements. Taking a lightning protection project for a weakcurrent equipment room as an example， the key parameters that influence the reliability of lighting protection for weak current equipment rooms are analyzed and obtained. The parameters include the spatial shield efficiency， transmission cable shield efficiency， terminal maximum pulse voltage limits， inductive voltage at the maximum split ring in equipment room cabling， pressurebalancing and discharging capability. The appraisal and computation are conducted on these key parameters， and a parameter list of lightning protection efficiency determination for weak current equipment rooms is presented.