CIVICRM Create API for event participate
Md Maidul Islam,

Bit difficult to understand from your question what you want to achieve. 

1 - Do you mean to add participant for an event? Then you can use Entity = Participant and Action = Create api

$result = civicrm_api3('Participant', 'create', [
  'event_id' =&gt; 3,
  'contact_id' =&gt; 51,
]);


2 - Do you mean to add participant for an event with all contact details in one call ? Then you can use Entity = Contact and Action = Create chain api

$params = [
    'display_name' =&gt; 'batman',
    'contact_type' =&gt; 'Individual',
    'api.address.create' =&gt; [
      'contact_id' =&gt; '$value.id',
      'location_type_id' =&gt; 6,
      'street_name' =&gt; 'Ambachtstraat',
      'street_number' =&gt; '23',
      'street_address' =&gt; 'Ambachtstraat 23',
      'postal_code' =&gt; '6971 BN',
      'country_id' =&gt; '1152',
      'city' =&gt; 'Brummen',
      'is_primary' =&gt; 1,
    ],
    'api.email.create' =&gt; [
      'contact_id' =&gt; '$value.id',
      'location_type_id' =&gt; 'Main',
      'email' =&gt; 'api@a-team.com',
      'is_primary' =&gt; 1,
    ],
    'api.phone.create' =&gt; [
      'contact_id' =&gt; '$value.id',
      'location_type_id' =&gt; 6,
      'phone' =&gt; '(123) 456-7890',
      'is_primary' =&gt; 1,
      'phone_type_id' =&gt; 1,
    ],
    'api.participant.create' =&gt; [
      'contact_id' =&gt; '$value.id',
      'event_id' =&gt; 2,
      'status_id' =&gt; 1,
      'role_id' =&gt; 1,
      'register_date' =&gt; '2007-07-21 00:00:00',
      'source' =&gt; 'Online Event Registration: API Testing',
      'custom_1' =&gt; 'custom string',
    ],
  ];
$result = civicrm_api3('Contact', 'create', $params);


3 - Do you mean to get participant of an event with all contact details in one call ?

   $params = array(
    'contact_id' =&gt; 2,
    'event_id' =&gt; 3,
    'api.contact.get' =&gt; 1,
    'api.email.get' =&gt; ['contact_id' =&gt; '$value.contact_id'],
    'api.address.get' =&gt; ['contact_id' =&gt; '$value.contact_id'],
    'api.phone.get' =&gt; ['contact_id' =&gt; '$value.contact_id'],
  );


HTH

Pradeep

Note: The params build above are not tested, but its the syntax on how one can build params when using chain api.

HTH

Pradeep