要在AWS账户之间建立私有连接，可以使用AWS Direct Connect或AWS VPN连接。以下是一个使用AWS Direct Connect连接两个账户的示例代码：

import boto3

def create_direct_connect_connection(vgw_id, dx_gateway_id, dx_location, customer_name, bandwidth):
    client = boto3.client('directconnect')
    
    response = client.create_connection(
        connectionName='MyDirectConnectConnection',
        location=dx_location,
        bandwidth=bandwidth,
        lagId='',
        providerName='MyProvider',
        requestDXCName='MyRequester',
        tagKey='Customer',
        tagValue=customer_name,
        amazonAddress="",
        awsDevice='',
        bgpAsn=65000,
        connectionId='',
        ownerAccountId='',
        vlan=1,
        tags=[
            {
                'key': 'Customer',
                'value': customer_name
            },
        ]
    )
    
    return response['connectionId']

# 使用示例
vgw_id = 'vgw-12345'
dx_gateway_id = 'dxgw-67890'
dx_location = 'EqSV5a'
customer_name = 'MyCustomer'
bandwidth = '1Gbps'

connection_id = create_direct_connect_connection(vgw_id, dx_gateway_id, dx_location, customer_name, bandwidth)
print(f"Connection ID: {connection_id}")

这个示例使用boto3库创建一个名为MyDirectConnectConnection的连接，连接的参数包括连接名称、地点、带宽、BGP ASN等。可以根据需要调整参数来创建连接。

另外，也可以使用AWS VPN连接两个账户。以下是一个使用AWS VPN连接的示例代码：

import boto3

def create_vpn_connection(vpn_gateway_id, customer_gateway_id, static_routes, customer_name):
    client = boto3.client('ec2')
    
    response = client.create_vpn_connection(
        CustomerGatewayId=customer_gateway_id,
        Type='ipsec.1',
        VpnGatewayId=vpn_gateway_id,
        Options={
            'StaticRoutesOnly': static_routes
        },
        TagSpecifications=[
            {
                'ResourceType': 'vpn-connection',
                'Tags': [
                    {
                        'Key': 'Customer',
                        'Value': customer_name
                    },
                ]
            },
        ]
    )
    
    return response['VpnConnection']['VpnConnectionId']

# 使用示例
vpn_gateway_id = 'vgw-12345'
customer_gateway_id = 'cgw-67890'
static_routes = True
customer_name = 'MyCustomer'

connection_id = create_vpn_connection(vpn_gateway_id, customer_gateway_id, static_routes, customer_name)
print(f"Connection ID: {connection_id}")

这个示例使用boto3库创建一个IPsec VPN连接，连接的参数包括VPN网关ID、用户网关ID、是否只使用静态路由等。可以根据需要调整参数来创建连接。

无论是使用AWS Direct Connect还是AWS VPN，都需要确保账户之间有正确的IAM权限，并且正确配置了网络设置。