A system for developing a third-party application, comprising: a vehicle-mounted device and a developer platform configured to communicate with each other; the vehicle-mounted device being configured to: obtain a vehicle signal, the vehicle signal comprising vehicle status information sent by each detection module through a vehicle communication network, or a control instruction to be sent to each actuator through the vehicle communication network, or the vehicle status information and the control instruction; and generate a corresponding application programming interface, API, according to a protocol analysis mode of the vehicle signal and API specifications, add the API to a software development kit, SDK, and send the API to the developer platform; and the developer platform being configured to publish the SDK so that a developer develops a third-party application according to the API in the SDK, wherein the vehicle-mounted device comprises: a protocol analyzing module and an API packaging module, wherein the protocol analyzing module is configured to analyze the vehicle signal to obtain the protocol analysis mode of the vehicle signal; and the API packaging module is configured to generate, through packaging, the corresponding API according to the protocol analysis mode and the API specifications. a vehicle-mounted device and a developer platform configured to communicate with each other; the vehicle-mounted device being configured to: obtain a vehicle signal, the vehicle signal comprising vehicle status information sent by each detection module through a vehicle communication network, or a control instruction to be sent to each actuator through the vehicle communication network, or the vehicle status information and the control instruction; and generate a corresponding application programming interface, API, according to a protocol analysis mode of the vehicle signal and API specifications, add the API to a software development kit, SDK, and send the API to the developer platform; and the developer platform being configured to publish the SDK so that a developer develops a third-party application according to the API in the SDK, wherein the vehicle-mounted device comprises: a protocol analyzing module and an API packaging module, wherein the protocol analyzing module is configured to analyze the vehicle signal to obtain the protocol analysis mode of the vehicle signal; and the API packaging module is configured to generate, through packaging, the corresponding API according to the protocol analysis mode and the API specifications. obtain a vehicle signal, the vehicle signal comprising vehicle status information sent by each detection module through a vehicle communication network, or a control instruction to be sent to each actuator through the vehicle communication network, or the vehicle status information and the control instruction; and generate a corresponding application programming interface, API, according to a protocol analysis mode of the vehicle signal and API specifications, add the API to a software development kit, SDK, and send the API to the developer platform; and the developer platform being configured to publish the SDK so that a developer develops a third-party application according to the API in the SDK, wherein the vehicle-mounted device comprises: a protocol analyzing module and an API packaging module, wherein the protocol analyzing module is configured to analyze the vehicle signal to obtain the protocol analysis mode of the vehicle signal; and the API packaging module is configured to generate, through packaging, the corresponding API according to the protocol analysis mode and the API specifications. a protocol analyzing module and an API packaging module, wherein the protocol analyzing module is configured to analyze the vehicle signal to obtain the protocol analysis mode of the vehicle signal; and the API packaging module is configured to generate, through packaging, the corresponding API according to the protocol analysis mode and the API specifications.