<apex:page controller="AddmultipleAccountController">
  <apex:form>
  <apex:pageBlock>
  <apex:pageBlockTable="{!ListAccount}" var="a" >
    <apex:inputField value="{!a.name}"/>
    <apex:inputField value="{!a.AccountNumber}"/>
    <apex:inputField value="{!a.Type}"/>
    <apex:inputField value="{!a.Industry}"/>
  </apex:pageBlockTable>
  <apex:pageBlockButtons>
   <apex:commandButton value="Add Accounts Row" action="{!addAccount}"/>
   <apex:commandButton value="Save Accounts" action="{!saveAccount}"/>
    </apex:pageBlockButtons>
   </apex:pageBlock>
  </apex:form>
</apex:page

public class AddmultipleAccountController {
 public List<Account> ListAccount{get; set;}

  public AddmultipleAccountController(ApexPages.StandardController myController)

  {
  ListAccount = new List<Account>();
   Account acc= new Account();
  ListAccount.add(acc);
  }

  public void addAccount()
  {
  Account acc= new Account();
  ListAccount.add(acc);
  }

  public PageReference saveAccount()
  {
  for(integer i=0; i<ListAccount.size(); i++)
  {
  insert ListAccount;
  }
  return Page.AllAccountssaved;
}

}