Jaydipsinh Parmar you can do using xml

create local.xml at app/design/frontend/your_package/our_theme/layout/ and past the code

   <reference name="header">

        <block type="checkout/cart_sidebar" name="cart_sidebar_header" template="checkout/cart/sidebar.phtml" >
                <action method="addItemRender"><type>simple</type><block>checkout/cart_item_renderer</block><template>checkout/cart/sidebar/default.phtml</template></action>
                <action method="addItemRender"><type>grouped</type><block>checkout/cart_item_renderer_grouped</block><template>checkout/cart/sidebar/default.phtml</template></action>
                <action method="addItemRender"><type>configurable</type><block>checkout/cart_item_renderer_configurable</block><template>checkout/cart/sidebar/default.phtml</template></action>
                <block type="core/text_list" name="cart_sidebar.extra_actions" as="extra_actions" translate="label" module="checkout">
                    <label>Shopping Cart Sidebar Extra Actions</label>
                </block>
            </block>
 </reference>

then add the echo $this->getChildHtml('cart_sidebar_header') to header.phtml

Jaydipsinh Parmar you can do using xml

create local.xml at app/design/frontend/your_package/our_theme/layout/ and past the code

       <default>

   <reference name="header">

        <block type="checkout/cart_sidebar" name="cart_sidebar_header" template="checkout/cart/cart_top.phtml" >
                <action method="addItemRender"><type>simple</type><block>checkout/cart_item_renderer</block><template>checkout/cart/sidebar/default.phtml</template></action>
                <action method="addItemRender"><type>grouped</type><block>checkout/cart_item_renderer_grouped</block><template>checkout/cart/sidebar/default.phtml</template></action>
                <action method="addItemRender"><type>configurable</type><block>checkout/cart_item_renderer_configurable</block><template>checkout/cart/sidebar/default.phtml</template></action>
                <block type="core/text_list" name="cart_sidebar.extra_actions" as="extra_actions" translate="label" module="checkout">
                    <label>Shopping Cart Sidebar Extra Actions</label>
                </block>
            </block>
 </reference>    </default>

then add the echo $this->getChildHtml('cart_sidebar_header') to header.phtml